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Hugo Villeneuve 9915753037 serial: sc16is7xx: fix unconditional activation of THRI interrupt 
Commit cc4c1d05eb ("sc16is7xx: Properly resume TX after stop") changed
behavior to unconditionnaly set the THRI interrupt in sc16is7xx_tx_proc().

For example when sending a 65 bytes message, and assuming the Tx FIFO is
initially empty, sc16is7xx_handle_tx() will write the first 64 bytes of the
message to the FIFO and sc16is7xx_tx_proc() will then activate THRI. When
the THRI IRQ is fired, the driver will write the remaining byte of the
message to the FIFO, and disable THRI by calling sc16is7xx_stop_tx().

When sending a 2 bytes message, sc16is7xx_handle_tx() will write the 2
bytes of the message to the FIFO and call sc16is7xx_stop_tx(), disabling
THRI. After sc16is7xx_handle_tx() exits, control returns to
sc16is7xx_tx_proc() which will unconditionally set THRI. When the THRI IRQ
is fired, the driver simply acknowledges the interrupt and does nothing
more, since all the data has already been written to the FIFO. This results
in 2 register writes and 4 register reads all for nothing and taking
precious cycles from the I2C/SPI bus.

Fix this by enabling the THRI interrupt only when we fill the Tx FIFO to
its maximum capacity and there are remaining bytes to send in the message.

Fixes: cc4c1d05eb ("sc16is7xx: Properly resume TX after stop")
Cc:  <stable@vger.kernel.org>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231211171353.2901416-7-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-12-15 14:20:28 +01:00
arch Merge 6.7-rc5 into tty-next 2023-12-11 09:10:42 +01:00
block block-6.7-2023-12-01 2023-12-02 06:39:30 +09:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression in ahash and hides the Kconfig sub-options for the jitter RNG. 2023-11-09 17:04:58 -08:00
Documentation dt-bindings: serial: imx: Properly describe the i.MX1 interrupts 2023-12-15 14:19:56 +01:00
drivers serial: sc16is7xx: fix unconditional activation of THRI interrupt 2023-12-15 14:20:28 +01:00
fs Char/Misc driver fixes for 6.7-rc5 2023-12-09 12:44:10 -08:00
include Merge 6.7-rc5 into tty-next 2023-12-11 09:10:42 +01:00
init As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
io_uring io_uring/af_unix: disable sending io_uring over sockets 2023-12-07 10:35:19 -07:00
ipc Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
kernel - Make sure tasks are thawed exactly and only once to avoid their state 2023-12-10 11:09:16 -08:00
lib 31 hotfixes. 10 of these address pre-6.6 issues and are marked cc:stable. 2023-12-08 08:36:23 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/madvise: add cond_resched() in madvise_cold_or_pageout_pte_range() 2023-12-06 16:12:50 -08:00
net Merge 6.7-rc5 into tty-next 2023-12-11 09:10:42 +01:00
rust Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
samples Landlock updates for v6.7-rc1 2023-11-03 09:28:53 -10:00
scripts 31 hotfixes. 10 of these address pre-6.6 issues and are marked cc:stable. 2023-12-08 08:36:23 -08:00
security + Features 2023-11-03 09:48:17 -10:00
sound Merge 6.7-rc5 into tty-next 2023-12-11 09:10:42 +01:00
tools Generic: 2023-12-10 10:46:46 -08:00
usr arch: Remove Itanium (IA-64) architecture 2023-09-11 08:13:17 +00:00
virt Revert "KVM: Prevent module exit until all VMs are freed" 2023-12-01 08:12:30 -08:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: generate kernel.spec in rpmbuild/SPECS/ 2023-10-03 20:49:09 +09:00
.mailmap .mailmap: add a new address mapping for Chester Lin 2023-12-06 16:12:45 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: drop Antti Palosaari 2023-12-06 16:12:49 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge 6.7-rc5 into tty-next 2023-12-11 09:10:42 +01:00
Makefile Linux 6.7-rc5 2023-12-10 14:33:40 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.