When uart_flush_buffer() runs before the DMA completion IRQ is delivered,
the following race can occur (all steps serialized by uart_port_lock):
1. DMA starts: tx_remaining = N, kfifo contains N bytes
2. DMA completes in hardware; IRQ is pending but not yet delivered
3. uart_flush_buffer() acquires the port lock and calls kfifo_reset(),
making kfifo_len() = 0 while tx_remaining remains N
4. uart_flush_buffer() releases the port lock
5. DMA IRQ fires; handle_tx_dma() acquires the port lock and calls
uart_xmit_advance(uport, tx_remaining) on an empty kfifo
uart_xmit_advance() increments kfifo->out by tx_remaining. Since
kfifo_reset() already set both in and out to 0, out wraps past in,
causing kfifo_len() to return UART_XMIT_SIZE - tx_remaining. The next
start_tx_dma() call then submits a DMA transfer of stale buffer data.
Fix this by snapshotting kfifo_len() at the start of handle_tx_dma()
and skipping uart_xmit_advance() when fifo_len < tx_remaining, which
indicates the kfifo was reset by a preceding flush.
Fixes: 2aaa43c707 ("tty: serial: qcom-geni-serial: add support for serial engine DMA")
Cc: stable <stable@kernel.org>
Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260506-serial-dma-stale-tx-buf-v1-1-e3ccb360d719@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
UART_RX_PAR_EN is incorrectly defined as bit 3, which triggers false
framing errors (S_GP_IRQ_1_EN) and causes received data to be dropped
when parity is enabled and the parity bit is 0.
Define UART_RX_PAR_EN as bit 4 of the SE_UART_RX_TRANS_CFG register, as
specified in the reference manual.
Fixes: c4f528795d ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Cc: stable <stable@kernel.org>
Signed-off-by: Prasanna S <prasanna.s@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://patch.msgid.link/20260428-serial-bit-correct-v1-1-9131ad5b97d8@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Drop the newline character from the middle of the printk message.
This avoids breaking the message into two lines unnecessarily.
Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://patch.msgid.link/20260319-drop_stray_n-v1-1-37fb619538bb@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When userspace enables flow control (CRTSCTS), the driver
deasserts RTS even when the receive buffer has space. This prevents the
peer device from transmitting, causing communication to stall.
The root cause is that the driver unconditionally uses manual RTS control
regardless of flow control mode. When CRTSCTS is set, the hardware should
automatically manage RTS based on buffer status, but the driver overrides
this by setting manual control.
Fix this by introducing port->manual_flow flag. In set_termios(), disable
manual flow when CRTSCTS is set. In set_mctrl(), only assert
SE_UART_MANUAL_RFR when manual_flow is active. Verified by enabling and
disabling hardware flow control with stty.
Signed-off-by: Anup Kulkarni <anup.kulkarni@oss.qualcomm.com>
Link: https://patch.msgid.link/20260310104155.339010-1-anup.kulkarni@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 10904d725f ("serial: qcom-geni: Enable PM runtime for serial
driver") caused BT init to fail during bootup on the RB2 platform,
preventing proper BT initialization. However, BT works correctly after
bootup completes.
The issue occurs when runtime PM is enabled and uart_add_one_port() is
called before wakeup IRQ setup. The uart_add_one_port() call activates
the device through runtime PM, which configures GPIOs to the "qup_x"
pinmux function during runtime resume. When wakeup IRQ registration
happens afterward using dev_pm_set_dedicated_wake_irq(), these GPIOs
are reset back to the "gpio" pinmux function, which impacts the RX GPIO
and leads to Bluetooth failures.
Fix this by ensuring wakeup IRQ setup is completed before calling
uart_add_one_port() to prevent the pinmux function conflict.
Fixes: 10904d725f ("serial: qcom-geni: Enable PM runtime for serial driver")
Reported-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Closes: https://lore.kernel.org/all/20251110101043.2108414-4-praveen.talari@oss.qualcomm.com/
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20260108041006.1874757-1-praveen.talari@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Qualcomm automotive SA8255p SoC relies on firmware to configure
platform resources, including clocks, interconnects and TLMM.
The driver requests resources operations over SCMI using power
and performance protocols.
The SCMI power protocol enables or disables resources like clocks,
interconnect paths, and TLMM (GPIOs) using runtime PM framework APIs,
such as resume/suspend, to control power states(on/off).
The SCMI performance protocol manages UART baud rates, with each baud
rate represented by a performance level. The driver uses the
dev_pm_opp_set_level() API to request the desired baud rate by
specifying the performance level.
Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20251110101043.2108414-5-praveen.talari@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The GENI serial driver currently handles power resource management
through calls to the statically defined geni_serial_resources_on() and
geni_serial_resources_off() functions. This approach reduces modularity
and limits support for platforms with diverse power management
mechanisms, including resource managed by firmware.
Improve modularity and enable better integration with platform-specific
power management, introduce support for runtime PM. Use
pm_runtime_resume_and_get() and pm_runtime_put_sync() within the
qcom_geni_serial_pm() callback to control resource power state
transitions based on UART power state changes.
Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20251110101043.2108414-4-praveen.talari@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here is a single driver fix for the qcom_geni_serial driver for
6.18-rc1. It has been in my tree for weeks, but missed being sent to
you for 6.17-final due to travel on my side.
This fixes a reported regression for this driver that prevents 6.17 from
working properly on this platform.
It has been in linux-next for many weeks with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty driver fix from Greg KH:
"Here is a single driver fix for the qcom_geni_serial driver. It has
been in my tree for weeks, but missed being sent to you for 6.17-final
due to travel on my side.
This fixes a reported regression for this driver that prevents 6.17
from working properly on this platform.
It has been in linux-next for many weeks with no reported issues"
* tag 'tty-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
serial: qcom-geni: Fix blocked task
Here are some small updates for tty/serial drivers for 6.18-rc1.
Not many changes overall, just the usual:
- abi cleanups and reworking of the tty functions by Jiri by adding
console lock guard logic
- 8250_platform driver updates
- qcom-geni driver updates
- other minor serial driver updates
- some more vt escape codes added
All of these have been in linux-next for a while with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial updates from Greg KH:
"Here are some small updates for tty/serial drivers for 6.18-rc1.
Not many changes overall, just the usual:
- abi cleanups and reworking of the tty functions by Jiri by adding
console lock guard logic
- 8250_platform driver updates
- qcom-geni driver updates
- other minor serial driver updates
- some more vt escape codes added
All of these have been in linux-next for a while with no reported
issues"
* tag 'tty-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (43 commits)
tty: serial: fix help message for SERIAL_CPM
serial: 8250: omap: Support wakeup pinctrl state on suspend
dt-bindings: serial: 8250_omap: Add wakeup pinctrl state
serial: max310x: improve interrupt handling
vt: move vc_saved_screen to within tty allocated judgment
Revert "m68k: make HPDCA and HPAPCI bools"
tty: remove redundant condition checks
tty/vt: Add missing return value for VT_RESIZE in vt_ioctl()
vt: remove redundant check on vc_mode in con_font_set()
serial: qcom-geni: Add DFS clock mode support to GENI UART driver
m68k: make HPDCA and HPAPCI bools
tty: n_gsm: Don't block input queue by waiting MSC
serial: qcom-geni: Fix off-by-one error in ida_alloc_range()
serdev: Drop dev_pm_domain_detach() call
serial: sc16is7xx: drop redundant conversion to bool
vt: add support for smput/rmput escape codes
serial: stm32: allow selecting console when the driver is module
serial: 8250_core: fix coding style issue
tty: serial: Modify the use of dev_err_probe()
s390/char/con3270: use tty_port_tty guard()
...
Add provision to load firmware of Serial engine for UART protocol from
Linux Execution Environment on running on APPS processor.
Co-developed-by: Mukesh Kumar Savaliya <mukesh.savaliya@oss.qualcomm.com>
Signed-off-by: Mukesh Kumar Savaliya <mukesh.savaliya@oss.qualcomm.com>
Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250911043256.3523057-7-viken.dadhaniya@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Revert commit 1afa70632c ("serial: qcom-geni: Enable PM runtime for
serial driver") and its dependent commit 86fa39dd6f ("serial:
qcom-geni: Enable Serial on SA8255p Qualcomm platforms") because the
first one causes regression - hang task on Qualcomm RB1 board (QRB2210)
and unable to use serial at all during normal boot:
INFO: task kworker/u16:0:12 blocked for more than 42 seconds.
Not tainted 6.17.0-rc1-00004-g53e760d89498 #9
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u16:0 state:D stack:0 pid:12 tgid:12 ppid:2 task_flags:0x4208060 flags:0x00000010
Workqueue: async async_run_entry_fn
Call trace:
__switch_to+0xe8/0x1a0 (T)
__schedule+0x290/0x7c0
schedule+0x34/0x118
rpm_resume+0x14c/0x66c
rpm_resume+0x2a4/0x66c
rpm_resume+0x2a4/0x66c
rpm_resume+0x2a4/0x66c
__pm_runtime_resume+0x50/0x9c
__driver_probe_device+0x58/0x120
driver_probe_device+0x3c/0x154
__driver_attach_async_helper+0x4c/0xc0
async_run_entry_fn+0x34/0xe0
process_one_work+0x148/0x290
worker_thread+0x2c4/0x3e0
kthread+0x118/0x1c0
ret_from_fork+0x10/0x20
The issue was reported on 12th of August and was ignored by author of
commits introducing issue for two weeks. Only after complaining author
produced a fix which did not work, so if original commits cannot be
reliably fixed for 5 weeks, they obviously are buggy and need to be
dropped.
Fixes: 1afa70632c ("serial: qcom-geni: Enable PM runtime for serial driver")
Reported-by: Alexey Klimov <alexey.klimov@linaro.org>
Closes: https://lore.kernel.org/all/DC0D53ZTNOBU.E8LSD5E5Z8TX@linaro.org/
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Alexey Klimov <alexey.klimov@linaro.org>
Reviewed-by: Alexey Klimov <alexey.klimov@linaro.org>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Link: https://lore.kernel.org/r/20250917010437.129912-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
GENI UART driver currently supports only non-DFS (Dynamic Frequency
Scaling) mode for source frequency selection. However, to operate correctly
in DFS mode, the GENI SCLK register must be programmed with the appropriate
DFS index. Failing to do so can result in incorrect frequency selection
Add support for Dynamic Frequency Scaling (DFS) mode in the GENI UART
driver by configuring the GENI_CLK_SEL register with the appropriate DFS
index. This ensures correct frequency selection when operating in DFS mode.
Replace the UART driver-specific logic for clock selection with the GENI
common driver function to obtain the desired frequency and corresponding
clock index. This improves maintainability and consistency across
GENI-based drivers.
Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250903063136.3015237-1-viken.dadhaniya@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The ida_alloc_range() function expects an inclusive range, meaning both
the start and end values are valid allocation targets. Passing nr_ports
as the upper bound allows allocation of an ID equal to nr_ports, which
is out of bounds when used as an index into the port array.
Fix this by subtracting 1 from nr_ports in both calls to ida_alloc_range(),
ensuring the allocated ID stays within the valid range
[start, nr_ports - 1].
This prevents potential out-of-bounds access when the allocated ID is used
as an index.
Fixes: 9391ab1ed9 ("serial: qcom-geni: Make UART port count configurable via Kconfig")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202508180815.R2nDyajs-lkp@intel.com/
Signed-off-by: Zong Jiang <quic_zongjian@quicinc.com>
Link: https://lore.kernel.org/r/20250827120319.1682835-1-quic_zongjian@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Replace the hardcoded GENI_UART_PORTS macro with a new Kconfig option
SERIAL_QCOM_GENI_UART_PORTS to allow platforms to configure the maximum
number of UART ports supported by the driver at build time.
This improves flexibility for platforms that require more than the
previously fixed number of UART ports, and avoids unnecessary allocation
for unused ports.
Signed-off-by: Zong Jiang <quic_zongjian@quicinc.com>
Link: https://lore.kernel.org/r/20250812054819.3748649-3-quic_zongjian@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Replace the static allocation of UART ports with dynamic allocation
using devm_kzalloc. This change removes the fixed-size array and instead
allocates each UART port structure on demand during probe, improving
memory efficiency and scalability.
Signed-off-by: Zong Jiang <quic_zongjian@quicinc.com>
Link: https://lore.kernel.org/r/20250812054819.3748649-2-quic_zongjian@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Qualcomm automotive SA8255p SoC relies on firmware to configure
platform resources, including clocks, interconnects and TLMM.
The driver requests resources operations over SCMI using power
and performance protocols.
The SCMI power protocol enables or disables resources like clocks,
interconnect paths, and TLMM (GPIOs) using runtime PM framework APIs,
such as resume/suspend, to control power states(on/off).
The SCMI performance protocol manages UART baud rates, with each baud
rate represented by a performance level. The driver uses the
dev_pm_opp_set_level() API to request the desired baud rate by
specifying the performance level.
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Praveen Talari <quic_ptalari@quicinc.com>
Link: https://lore.kernel.org/r/20250721174532.14022-9-quic_ptalari@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The GENI serial driver currently handles power resource management
through calls to the statically defined geni_serial_resources_on() and
geni_serial_resources_off() functions. This approach reduces modularity
and limits support for platforms with diverse power management
mechanisms, including resource managed by firmware.
Improve modularity and enable better integration with platform-specific
power management, introduce support for runtime PM. Use
pm_runtime_resume_and_get() and pm_runtime_put_sync() within the
qcom_geni_serial_pm() callback to control resource power state
transitions based on UART power state changes.
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Praveen Talari <quic_ptalari@quicinc.com>
Link: https://lore.kernel.org/r/20250721174532.14022-8-quic_ptalari@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Facilitates future modifications within the new function,
leading to better readability and maintainability of the code.
Move the code that handles the actual logic of clock-rate
calculations to a separate function geni_serial_set_rate()
which enhances code readability.
Signed-off-by: Praveen Talari <quic_ptalari@quicinc.com>
Link: https://lore.kernel.org/r/20250721174532.14022-7-quic_ptalari@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Supports use in PM system/runtime frameworks, helping to distinguish new
resource control mechanisms and facilitate future modifications within
the new API.
The code that handles the actual enable or disable of resources like clock
and ICC paths to a separate function (geni_serial_resources_on() and
geni_serial_resources_off()) which enhances code readability.
Introduced minor return checks in newly added function APIs to enhance
error detection and prevent silent failures.
Signed-off-by: Praveen Talari <quic_ptalari@quicinc.com>
Link: https://lore.kernel.org/r/20250721174532.14022-6-quic_ptalari@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Enhances code readability and future modifications within the new API.
Move the code that handles the actual initialization of resources
like clock and ICC paths to a separate function, making the
probe function cleaner.
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Praveen Talari <quic_ptalari@quicinc.com>
Link: https://lore.kernel.org/r/20250721174532.14022-5-quic_ptalari@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Enable the use of the RTS pin for direction control in half-duplex modes to
prevent data collisions. Utilize the rs485 structure and callbacks in the
serial core framework to support half-duplex modes. Implement support for
the TIOCSRS485 IOCTL value and the struct serial_rs485.
Signed-off-by: Anup Kulkarni <quic_anupkulk@quicinc.com>
Link: https://lore.kernel.org/r/20250603110145.3835111-1-quic_anupkulk@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Current GENI UART driver supports Max Baud rate up to 4 Mbps.
Add support to increase maximum baud rate to 8 Mbps.
Signed-off-by: Jyothi Kumar Seerapu <quic_jseerapu@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250523103721.5042-1-quic_jseerapu@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The absence of an alias in the device tree results in an invalid line
number, causing the driver probe to fail for GENI serial.
To prevent probe failures, dynamically assign line numbers if an alias is
not present in the device tree for non-console ports.
Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
Link: https://lore.kernel.org/r/20250327070711.2585887-1-quic_vdadhani@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Drop the unnecessary "_sys" infix from the suspend PM ops.
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20241009145110.16847-10-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Serial drivers should not be dropping characters themselves, but at
least drop the unused 'drop' parameter from the receive handler for now.
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20241009145110.16847-9-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Drop the unnecessary WARN() in case the TTY buffers are ever full in
favour of a rate limited dev_err() which doesn't kill the machine when
panic_on_warn is set.
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20241009145110.16847-8-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The receiver is supposed to be enabled in the startup() callback and not
in set_termios() which is called also during console setup.
This specifically avoids accepting input before the port has been opened
(and interrupts enabled), something which can also break the GENI
firmware (cancel fails and after abort, the "stale" counter handling
appears to be broken so that later input is not processed until twelve
chars have been received).
There also does not appear to be any need to keep the receiver disabled
while updating the port settings.
Since commit 6f3c3cafb1 ("serial: qcom-geni: disable interrupts during
console writes") the calls to manipulate the secondary interrupts, which
were done without holding the port lock, can also lead to the receiver
being left disabled when set_termios() races with the console code (e.g.
when init opens the tty during boot). This can manifest itself as a
serial getty not accepting input.
The calls to stop and start rx in set_termios() can similarly race with
DMA completion and, for example, cause the DMA buffer to be unmapped
twice or the mapping to be leaked.
Fix this by only enabling the receiver during startup and while holding
the port lock to avoid racing with the console code.
Fixes: 6f3c3cafb1 ("serial: qcom-geni: disable interrupts during console writes")
Fixes: 2aaa43c707 ("tty: serial: qcom-geni-serial: add support for serial engine DMA")
Fixes: c4f528795d ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Cc: stable@vger.kernel.org # 6.3
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20241009145110.16847-6-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Make sure to wait for the DMA transfer to complete when cancelling the
rx command on stop_rx(). This specifically prevents the DMA completion
interrupt from firing after rx has been restarted, something which can
lead to an IOMMU fault and hosed rx when the interrupt handler unmaps
the DMA buffer for the new command:
qcom_geni_serial 988000.serial: serial engine reports 0 RX bytes in!
arm-smmu 15000000.iommu: FSR = 00000402 [Format=2 TF], SID=0x563
arm-smmu 15000000.iommu: FSYNR0 = 00210013 [S1CBNDX=33 WNR PLVL=3]
Bluetooth: hci0: command 0xfc00 tx timeout
Bluetooth: hci0: Reading QCA version information failed (-110)
Also add the missing state machine reset which is needed in case
cancellation fails.
Fixes: 2aaa43c707 ("tty: serial: qcom-geni-serial: add support for serial engine DMA")
Cc: stable@vger.kernel.org # 6.3
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20241009145110.16847-5-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A commit adding back the stopping of tx on port shutdown failed to add
back the locking which had also been removed by commit e83766334f
("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART
shutdown").
Holding the port lock is needed to serialise against the console code,
which may update the interrupt enable register and access the port
state.
Fixes: d8aca2f968 ("tty: serial: qcom-geni-serial: stop operations in progress at shutdown")
Fixes: 947cc4ecc0 ("serial: qcom-geni: fix soft lockup on sw flow control and suspend")
Cc: stable@vger.kernel.org # 6.3
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20241009145110.16847-4-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 35781d8356.
Hibernation is not supported on Qualcomm platforms with mainline
kernels yet a broken vendor implementation for the GENI serial driver
made it upstream.
This is effectively dead code that cannot be tested and should just be
removed, but if these paths were ever hit for an open non-console port
they would crash the machine as the driver would fail to enable clocks
during restore() (i.e. all ports would have to be closed by drivers and
user space before hibernating the system to avoid this as a comment in
the code hinted at).
The broken implementation also added a random call to enable the
receiver in the port setup code where it does not belong and which
enables the receiver prematurely for console ports.
Fixes: 35781d8356 ("tty: serial: qcom-geni-serial: Add support for Hibernation feature")
Cc: stable@vger.kernel.org # 6.2
Cc: Aniket Randive <quic_arandive@quicinc.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20241009145110.16847-3-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The polled console (KGDB/KDB) implementation must not call port setup
unconditionally as the port may already be in use by the console or a
getty.
Only make sure that the receiver is enabled, but do not enable any
device interrupts.
Fixes: d8851a96ba ("tty: serial: qcom-geni-serial: Add a poll_init() function")
Cc: stable@vger.kernel.org # 6.4
Cc: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20241009145110.16847-2-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After commit 0edb555a65 ("platform: Make platform_driver::remove()
return void") .remove() is (again) the right callback to implement for
platform drivers.
Convert all platform drivers below drivers/tty/serial to use .remove(),
with the eventual goal to drop struct platform_driver::remove_new(). As
.remove() and .remove_new() have the same prototypes, conversion is done
by just changing the structure member name in the driver initializer.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20241007205803.444994-7-u.kleine-koenig@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The polled UART operations are used by the kernel debugger (KDB, KGDB),
which can interrupt the kernel at any point in time. The current
Qualcomm GENI implementation does not really work when there is on-going
serial output as it inadvertently "hijacks" the current tx command,
which can result in both the initial debugger output being corrupted as
well as the corruption of any on-going serial output (up to 4k
characters) when execution resumes:
0190: abcdefghijklmnopqrstuvwxyz0123456789 0190: abcdefghijklmnopqrstuvwxyz0123456789
0191: abcdefghijklmnop[ 50.825552] sysrq: DEBUG
qrstuvwxyz0123456789 0191: abcdefghijklmnopqrstuvwxyz0123456789
Entering kdb (current=0xffff53510b4cd280, pid 640) on processor 2 due to Keyboard Entry
[2]kdb> go
omlji3h3h2g2g1f1f0e0ezdzdycycxbxbwawav :t72r2rp
o9n976k5j5j4i4i3h3h2g2g1f1f0e0ezdzdycycxbxbwawavu:t7t8s8s8r2r2q0q0p
o9n9n8ml6k6k5j5j4i4i3h3h2g2g1f1f0e0ezdzdycycxbxbwawav v u:u:t9t0s4s4rq0p
o9n9n8m8m7l7l6k6k5j5j40q0p p o
o9n9n8m8m7l7l6k6k5j5j4i4i3h3h2g2g1f1f0e0ezdzdycycxbxbwawav :t8t9s4s4r4r4q0q0p
Fix this by making sure that the polled output implementation waits for
the tx fifo to drain before cancelling any on-going longer transfers. As
the polled code cannot take any locks, leave the state variables as they
are and instead make sure that the interrupt handler always starts a new
tx command when there is data in the write buffer.
Since the debugger can interrupt the interrupt handler when it is
writing data to the tx fifo, it is currently not possible to fully
prevent losing up to 64 bytes of tty output on resume.
Fixes: c4f528795d ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Cc: stable@vger.kernel.org # 4.17
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240906131336.23625-9-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Disable the GENI interrupts during console writes to reduce the risk of
having interrupt handlers spinning on the port lock on other cores for
extended periods of time.
This can, for example, reduce the total amount of time spent in the
interrupt handler during boot of the x1e80100 CRD by up to a factor nine
(e.g. from 274 ms to 30 ms) while the worst case processing time drops
from 19 ms to 8 ms.
Fixes: c4f528795d ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240906131336.23625-8-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Qualcomm serial console implementation is broken and can lose
characters when the serial port is also used for tty output.
Specifically, the console code only waits for the current tx command to
complete when all data has already been written to the fifo. When there
are on-going longer transfers this often means that console output is
lost when the console code inadvertently "hijacks" the current tx
command instead of starting a new one.
This can, for example, be observed during boot when console output that
should have been interspersed with init output is truncated:
[ 9.462317] qcom-snps-eusb2-hsphy fde000.phy: Registered Qcom-eUSB2 phy
[ OK ] Found device KBG50ZNS256G KIOXIA Wi[ 9.471743ndows.
[ 9.539915] xhci-hcd xhci-hcd.0.auto: xHCI Host Controller
Add a new state variable to track how much data has been written to the
fifo and use it to determine when the fifo and shift register are both
empty. This is needed since there is currently no other known way to
determine when the shift register is empty.
This in turn allows the console code to interrupt long transfers without
losing data.
Note that the oops-in-progress case is similarly broken as it does not
cancel any active command and also waits for the wrong status flag when
attempting to drain the fifo (TX_FIFO_NOT_EMPTY_EN is only set when
cancelling a command leaves data in the fifo).
Fixes: c4f528795d ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Fixes: a1fee899e5 ("tty: serial: qcom_geni_serial: Fix softlock")
Fixes: 9e957a1550 ("serial: qcom-geni: Don't cancel/abort if we can't get the port lock")
Cc: stable@vger.kernel.org # 4.17
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240906131336.23625-7-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With a small modification the qcom_geni_serial_poll_bit() function
could be used to poll more than just a single bit. Let's generalize
it. We'll make the qcom_geni_serial_poll_bit() into just a wrapper of
the general function.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240610152420.v4.5.Ic6411eab8d9d37acc451705f583fb535cd6dadb2@changeid
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240906131336.23625-6-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The "offset" passed in should be unsigned since it's always a positive
offset from our memory mapped IO.
The "field" should be u32 since we're anding it with a 32-bit value
read from the device.
Suggested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240610152420.v4.4.I24a0de52dd7336908df180fa6b698e001f3aff82@changeid
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240906131336.23625-5-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 663abb1a7a ("tty: serial: qcom_geni_serial: Fix UART hang")
addressed an issue with stalled tx after the console code interrupted
the last bytes of a tx command by reenabling the watermark interrupt if
there is data in write buffer. This can however break software flow
control by re-enabling tx after the user has stopped it.
Address the original issue by not clearing the CMD_DONE flag after
polling for command completion. This allows the interrupt handler to
start another transfer when the CMD_DONE interrupt has not been disabled
due to flow control.
Fixes: c4f528795d ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Fixes: 663abb1a7a ("tty: serial: qcom_geni_serial: Fix UART hang")
Cc: stable@vger.kernel.org # 4.17
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240906131336.23625-3-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The qcom_geni_serial_poll_bit() can be used to wait for events like
command completion and is supposed to wait for the time it takes to
clear a full fifo before timing out.
As noted by Doug, the current implementation does not account for start,
stop and parity bits when determining the timeout. The helper also does
not currently account for the shift register and the two-word
intermediate transfer register.
A too short timeout can specifically lead to lost characters when
waiting for a transfer to complete as the transfer is cancelled on
timeout.
Instead of determining the poll timeout on every call, store the fifo
timeout when updating it in set_termios() and make sure to take the
shift and intermediate registers into account. Note that serial core has
already added a 20 ms margin to the fifo timeout.
Also note that the current uart_fifo_timeout() interface does
unnecessary calculations on every call and did not exist in earlier
kernels so only store its result once. This facilitates backports too as
earlier kernels can derive the timeout from uport->timeout, which has
since been removed.
Fixes: c4f528795d ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Cc: stable@vger.kernel.org # 4.17
Reported-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240906131336.23625-2-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Qualcomm GENI serial driver did not handle buffer flushing and used
to print discarded characters when the circular buffer was cleared.
Since commit 1788cf6a91 ("tty: serial: switch from circ_buf to kfifo")
this instead resulted in a hard lockup due to
qcom_geni_serial_send_chunk_fifo() spinning indefinitely in the
interrupt handler.
The underlying bugs have now been fixed, but make sure to output NUL
characters instead of killing the machine if a similar driver bug is
ever reintroduced.
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240704101805.30612-4-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Qualcomm GENI serial driver does not handle buffer flushing and used
to continue printing discarded characters when the circular buffer was
cleared. Since commit 1788cf6a91 ("tty: serial: switch from circ_buf
to kfifo") this instead results in a hard lockup due to
qcom_geni_serial_send_chunk_fifo() spinning indefinitely in the
interrupt handler.
This is easily triggered by interrupting a command such as dmesg in a
serial console but can also happen when stopping a serial getty on
reboot.
Implement the flush_buffer() callback and use it to cancel any active TX
command when the write buffer has been emptied.
Reported-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/lkml/20240610222515.3023730-1-dianders@chromium.org/
Fixes: 1788cf6a91 ("tty: serial: switch from circ_buf to kfifo")
Fixes: a1fee899e5 ("tty: serial: qcom_geni_serial: Fix softlock")
Cc: stable@vger.kernel.org # 5.0
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240704101805.30612-3-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The stop_tx() callback is used to implement software flow control and
must not discard data as the Qualcomm GENI driver is currently doing
when there is an active TX command.
Cancelling an active command can also leave data in the hardware FIFO,
which prevents the watermark interrupt from being enabled when TX is
later restarted. This results in a soft lockup and is easily triggered
by stopping TX using software flow control in a serial console but this
can also happen after suspend.
Fix this by only stopping any active command, and effectively clearing
the hardware fifo, when shutting down the port. When TX is later
restarted, a transfer command may need to be issued to discard any stale
data that could prevent the watermark interrupt from firing.
Fixes: c4f528795d ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Cc: stable@vger.kernel.org # 4.17
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240704101805.30612-2-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Marek reports, that the -next commit 1788cf6a91 (tty: serial: switch
from circ_buf to kfifo) broke meson_uart and qcom_geni_serial. The
commit mistakenly advanced the kfifo twice: once by
uart_fifo_get()/kfifo_out() and second time by uart_xmit_advance().
To advance the fifo only once, drop the superfluous uart_xmit_advance()
from both.
To count the TX statistics properly, use uart_fifo_out() in
qcom_geni_serial (meson_uart_start_tx() already uses that).
I checked all other uses of uart_xmit_advance() and they appear correct:
either they are finishing DMA transfers or are after peek/linear_ptr
(i.e. they do not advance fifo).
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: 1788cf6a91 ("tty: serial: switch from circ_buf to kfifo")
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20240416054825.6211-1-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Switch from struct circ_buf to proper kfifo. kfifo provides much better
API, esp. when wrap-around of the buffer needs to be taken into account.
Look at pl011_dma_tx_refill() or cpm_uart_tx_pump() changes for example.
Kfifo API can also fill in scatter-gather DMA structures, so it easier
for that use case too. Look at lpuart_dma_tx() for example. Note that
not all drivers can be converted to that (like atmel_serial), they
handle DMA specially.
Note that usb-serial uses kfifo for TX for ages.
omap needed a bit more care as it needs to put a char into FIFO to start
the DMA transfer when OMAP_DMA_TX_KICK is set. In that case, we have to
do kfifo_dma_out_prepare twice: once to find out the tx_size (to find
out if it is worths to do DMA at all -- size >= 4), the second time for
the actual transfer.
All traces of circ_buf are removed from serial_core.h (and its struct
uart_state).
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Al Cooper <alcooperx@gmail.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
Cc: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Taichi Sugaya <sugaya.taichi@socionext.com>
Cc: Takao Orito <orito.takao@socionext.com>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>
Cc: Pali Rohár <pali@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Hammer Hsieh <hammerh0314@gmail.com>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Timur Tabi <timur@kernel.org>
Cc: Michal Simek <michal.simek@amd.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20240405060826.2521-13-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here is the big set of TTY/Serial driver updates and cleanups for
6.9-rc1. Included in here are:
- more tty cleanups from Jiri
- loads of 8250 driver cleanups from Andy
- max310x driver updates
- samsung serial driver updates
- uart_prepare_sysrq_char() updates for many drivers
- platform driver remove callback void cleanups
- stm32 driver updates
- other small tty/serial driver updates
All of these have been in linux-next for a long time with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty / serial driver updates from Greg KH:
"Here is the big set of TTY/Serial driver updates and cleanups for
6.9-rc1. Included in here are:
- more tty cleanups from Jiri
- loads of 8250 driver cleanups from Andy
- max310x driver updates
- samsung serial driver updates
- uart_prepare_sysrq_char() updates for many drivers
- platform driver remove callback void cleanups
- stm32 driver updates
- other small tty/serial driver updates
All of these have been in linux-next for a long time with no reported
issues"
* tag 'tty-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (199 commits)
dt-bindings: serial: stm32: add power-domains property
serial: 8250_dw: Replace ACPI device check by a quirk
serial: Lock console when calling into driver before registration
serial: 8250_uniphier: Switch to use uart_read_port_properties()
serial: 8250_tegra: Switch to use uart_read_port_properties()
serial: 8250_pxa: Switch to use uart_read_port_properties()
serial: 8250_omap: Switch to use uart_read_port_properties()
serial: 8250_of: Switch to use uart_read_port_properties()
serial: 8250_lpc18xx: Switch to use uart_read_port_properties()
serial: 8250_ingenic: Switch to use uart_read_port_properties()
serial: 8250_dw: Switch to use uart_read_port_properties()
serial: 8250_bcm7271: Switch to use uart_read_port_properties()
serial: 8250_bcm2835aux: Switch to use uart_read_port_properties()
serial: 8250_aspeed_vuart: Switch to use uart_read_port_properties()
serial: port: Introduce a common helper to read properties
serial: core: Add UPIO_UNKNOWN constant for unknown port type
serial: core: Move struct uart_port::quirks closer to possible values
serial: sh-sci: Call sci_serial_{in,out}() directly
serial: core: only stop transmit when HW fifo is empty
serial: pch: Use uart_prepare_sysrq_char().
...
This reverts commit 5c7e105cd1.
As identified by KASAN, the simplification done by the cleanup patch
was not legal.
>From tracing through the code, it can be seen that we're transmitting
from a 4096-byte circular buffer. We copy anywhere from 1-4 bytes from
it each time. The simplification runs into trouble when we get near
the end of the circular buffer. For instance, we might start out with
xmit->tail = 4094 and we want to transfer 4 bytes. With the code
before simplification this was no problem. We'd read buf[4094],
buf[4095], buf[0], and buf[1]. With the new code we'll do a
memcpy(&buf[4094], 4) which reads 2 bytes past the end of the buffer
and then skips transmitting what's at buf[0] and buf[1].
KASAN isn't 100% consistent at reporting this for me, but to be extra
confident in the analysis, I added traces of the tail and tx_bytes and
then wrote a test program:
while true; do
echo -n "abcdefghijklmnopqrstuvwxyz0" > /dev/ttyMSM0
sleep .1
done
I watched the traces over SSH and saw:
qcom_geni_serial_send_chunk_fifo: 4093 4
qcom_geni_serial_send_chunk_fifo: 1 3
Which indicated that one byte should be missing. Sure enough the
output that should have been:
abcdefghijklmnopqrstuvwxyz0
In one case was actually missing a byte:
abcdefghijklmnopqrstuvwyz0
Running "ls -al" on large directories also made the missing bytes
obvious since columns didn't line up.
While the original code may not be the most elegant, we only talking
about copying up to 4 bytes here. Let's just go back to the code that
worked.
Fixes: 5c7e105cd1 ("tty: serial: simplify qcom_geni_serial_send_chunk_fifo()")
Cc: stable <stable@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240304174952.1.I920a314049b345efd1f69d708e7f74d2213d0b49@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As of commit d7402513c9 ("arm64: smp: IPI_CPU_STOP and
IPI_CPU_CRASH_STOP should try for NMI"), if we've got pseudo-NMI
enabled then we'll use it to stop CPUs at panic time. This is nice,
but it does mean that there's a pretty good chance that we'll end up
stopping a CPU while it holds the port lock for the console
UART. Specifically, I see a CPU get stopped while holding the port
lock nearly 100% of the time on my sc7180-trogdor based Chromebook by
enabling the "buddy" hardlockup detector and then doing:
sysctl -w kernel.hardlockup_all_cpu_backtrace=1
sysctl -w kernel.hardlockup_panic=1
echo HARDLOCKUP > /sys/kernel/debug/provoke-crash/DIRECT
UART drivers are _supposed_ to handle this case OK and this is why
UART drivers check "oops_in_progress" and only do a "trylock" in that
case. However, before we enabled pseudo-NMI to stop CPUs it wasn't a
very well-tested situation.
Now that we're testing the situation a lot, it can be seen that the
Qualcomm GENI UART driver is pretty broken. Specifically, when I run
my test case and look at the console output I just see a bunch of
garbled output like:
[ 201.069084] NMI backtrace[ 201.069084] NM[ 201.069087] CPU: 6
PID: 10296 Comm: dnsproxyd Not tainted 6.7.0-06265-gb13e8c0ede12
#1 01112b9f14923cbd0b[ 201.069090] Hardware name: Google Lazor
([ 201.069092] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DI[
201.069095] pc : smp_call_function_man[ 201.069099]
That's obviously not so great. This happens because each call to the
console driver exits after the data has been written to the FIFO but
before it's actually been flushed out of the serial port. When we have
multiple calls into the console one after the other then (if we can't
get the lock) each call tells the UART to throw away any data in the
FIFO that hadn't been transferred yet.
I've posted up a patch to change the arm64 core to avoid this
situation most of the time [1] much like x86 seems to do, but even if
that patch lands the GENI driver should still be fixed.
>From testing, it appears that we can just delete the cancel/abort in
the case where we weren't able to get the UART lock and the output
looks good. It makes sense that we'd be able to do this since that
means we'll just call into __qcom_geni_serial_console_write() and
__qcom_geni_serial_console_write() looks much like
qcom_geni_serial_poll_put_char() but with a loop. However, it seems
safest to poll the FIFO and make sure it's empty before our
transfer. This should reliably make sure that we're not
interrupting/clobbering any existing transfers.
As part of this change, we'll also avoid re-setting up a TX at the end
of the console write function if we weren't able to get the lock,
since accessing "port->tx_remaining" without the lock is not
safe. This is only needed to re-start userspace initiated transfers.
[1] https://lore.kernel.org/r/20231207170251.1.Id4817adef610302554b8aa42b090d57270dc119c@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240112150307.2.Idb1553d1d22123c377f31eacb4486432f6c9ac8d@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().
Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231110152927.70601-32-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When a serial port is used for kernel console output, then all
modifications to the UART registers which are done from other contexts,
e.g. getty, termios, are interference points for the kernel console.
So far this has been ignored and the printk output is based on the
principle of hope. The rework of the console infrastructure which aims to
support threaded and atomic consoles, requires to mark sections which
modify the UART registers as unsafe. This allows the atomic write function
to make informed decisions and eventually to restore operational state. It
also allows to prevent the regular UART code from modifying UART registers
while printk output is in progress.
All modifications of UART registers are guarded by the UART port lock,
which provides an obvious synchronization point with the console
infrastructure.
To avoid adding this functionality to all UART drivers, wrap the
spin_[un]lock*() invocations for uart_port::lock into helper functions
which just contain the spin_[un]lock*() invocations for now. In a
subsequent step these helpers will gain the console synchronization
mechanisms.
Converted with coccinelle. No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20230914183831.587273-50-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
