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James Hutchinson f51db48c12 media: m88ds3103: serialize reset messages in m88ds3103_set_frontend 
[ Upstream commit 981fbe3da2 ]

Ref: https://bugzilla.kernel.org/show_bug.cgi?id=199323

Users are experiencing problems with the DVBSky S960/S960C USB devices
since the following commit:

9d659ae: ("locking/mutex: Add lock handoff to avoid starvation")

The device malfunctions after running for an indeterminable period of
time, and the problem can only be cleared by rebooting the machine.

It is possible to encourage the problem to surface by blocking the
signal to the LNB.

Further debugging revealed the cause of the problem.

In the following capture:
- thread #1325 is running m88ds3103_set_frontend
- thread #42 is running ts2020_stat_work

a> [1325] usb 1-1: dvb_usb_v2_generic_io: >>> 08 68 02 07 80
   [1325] usb 1-1: dvb_usb_v2_generic_io: <<< 08
   [42] usb 1-1: dvb_usb_v2_generic_io: >>> 09 01 01 68 3f
   [42] usb 1-1: dvb_usb_v2_generic_io: <<< 08 ff
   [42] usb 1-1: dvb_usb_v2_generic_io: >>> 08 68 02 03 11
   [42] usb 1-1: dvb_usb_v2_generic_io: <<< 07
   [42] usb 1-1: dvb_usb_v2_generic_io: >>> 09 01 01 60 3d
   [42] usb 1-1: dvb_usb_v2_generic_io: <<< 07 ff
b> [1325] usb 1-1: dvb_usb_v2_generic_io: >>> 08 68 02 07 00
   [1325] usb 1-1: dvb_usb_v2_generic_io: <<< 07
   [42] usb 1-1: dvb_usb_v2_generic_io: >>> 08 68 02 03 11
   [42] usb 1-1: dvb_usb_v2_generic_io: <<< 07
   [42] usb 1-1: dvb_usb_v2_generic_io: >>> 09 01 01 60 21
   [42] usb 1-1: dvb_usb_v2_generic_io: <<< 07 ff
   [42] usb 1-1: dvb_usb_v2_generic_io: >>> 08 68 02 03 11
   [42] usb 1-1: dvb_usb_v2_generic_io: <<< 07
   [42] usb 1-1: dvb_usb_v2_generic_io: >>> 09 01 01 60 66
   [42] usb 1-1: dvb_usb_v2_generic_io: <<< 07 ff
   [1325] usb 1-1: dvb_usb_v2_generic_io: >>> 08 68 02 03 11
   [1325] usb 1-1: dvb_usb_v2_generic_io: <<< 07
   [1325] usb 1-1: dvb_usb_v2_generic_io: >>> 08 60 02 10 0b
   [1325] usb 1-1: dvb_usb_v2_generic_io: <<< 07

Two i2c messages are sent to perform a reset in m88ds3103_set_frontend:

  a. 0x07, 0x80
  b. 0x07, 0x00

However, as shown in the capture, the regmap mutex is being handed over
to another thread (ts2020_stat_work) in between these two messages.

>From here, the device responds to every i2c message with an 07 message,
and will only return to normal operation following a power cycle.

Use regmap_multi_reg_write to group the two reset messages, ensuring
both are processed before the regmap mutex is unlocked.

Signed-off-by: James Hutchinson <jahutchinson99@googlemail.com>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-05-31 06:46:32 -07:00
arch x86/mce: Handle varying MCA bank counts 2019-05-31 06:46:30 -07:00
block block: sed-opal: fix IOC_OPAL_ENABLE_DISABLE_MBR 2019-05-31 06:46:24 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: ccm - fix incompatibility between "ccm" and "ccm_base" 2019-05-22 07:37:43 +02:00
Documentation arm64: errata: Add workaround for Cortex-A76 erratum #1463225 2019-05-31 06:46:03 -07:00
drivers media: m88ds3103: serialize reset messages in m88ds3103_set_frontend 2019-05-31 06:46:32 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs chardev: add additional check for minor range overlap 2019-05-31 06:46:27 -07:00
include tinydrm/mipi-dbi: Use dma-safe buffers for all SPI transfers 2019-05-31 06:46:32 -07:00
init init: initialize jump labels before command line option parsing 2019-05-16 19:41:23 +02:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel rcuperf: Fix cleanup path for invalid perf_type strings 2019-05-31 06:46:30 -07:00
lib kobject: Don't trigger kobject_uevent(KOBJ_REMOVE) twice. 2019-05-31 06:46:28 -07:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm hugetlb: use same fault hash key for shared and private mappings 2019-05-22 07:37:40 +02:00
net batman-adv: allow updating DAT entry timeouts on incoming ARP Replies 2019-05-31 06:46:31 -07:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:10:11 +01:00
scripts fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock 2019-05-08 07:21:51 +02:00
security selinux: avoid uninitialized variable warning 2019-05-31 06:46:31 -07:00
sound ASoC: fsl_utils: fix a leaked reference by adding missing of_node_put 2019-05-31 06:46:28 -07:00
tools selftests/bpf: ksym_search won't check symbols exists 2019-05-31 06:46:25 -07:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: arm/arm64: Ensure vcpu target is unset on reset failure 2019-05-25 18:23:44 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS platform/x86: Add Intel AtomISP2 dummy / power-management driver 2019-04-20 09:16:02 +02:00
Makefile Linux 4.19.46 2019-05-25 18:23:48 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.