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Daniel Thompson 61bae00000 backlight: pwm_bl: Improve bootloader/kernel device handover
commit 79fad92f2e596f5a8dd085788a24f540263ef887 upstream.

Currently there are (at least) two problems in the way pwm_bl starts
managing the enable_gpio pin. Both occur when the backlight is initially
off and the driver finds the pin not already in output mode and, as a
result, unconditionally switches it to output-mode and asserts the signal.

Problem 1: This could cause the backlight to flicker since, at this stage
in driver initialisation, we have no idea what the PWM and regulator are
doing (an unconfigured PWM could easily "rest" at 100% duty cycle).

Problem 2: This will cause us not to correctly honour the
post_pwm_on_delay (which also risks flickers).

Fix this by moving the code to configure the GPIO output mode until after
we have examines the handover state. That allows us to initialize
enable_gpio to off if the backlight is currently off and on if the
backlight is on.

Cc: stable@vger.kernel.org
Reported-by: Marek Vasut <marex@denx.de>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Marek Vasut <marex@denx.de>
Tested-by: Marek Vasut <marex@denx.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-07-05 19:13:55 +02:00
arch ARM: dts: at91: add pinctrl-{names, 0} for all gpios 2024-07-05 19:13:54 +02:00
block bio: fix page leak bio_add_hw_page failure 2024-07-05 19:13:40 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2024-07-05 19:10:21 +02:00
crypto init: add dsm gpl source 2024-07-05 18:00:04 +02:00
Documentation lkdtm: replace SCSI_DISPATCH_CMD with SCSI_QUEUE_RQ 2024-07-05 19:12:05 +02:00
drivers backlight: pwm_bl: Improve bootloader/kernel device handover 2024-07-05 19:13:55 +02:00
fs fuse: flush extending writes 2024-07-05 19:13:54 +02:00
include time: Handle negative seconds correctly in timespec64_to_ns() 2024-07-05 19:13:39 +02:00
init init: add dsm gpl source 2024-07-05 18:00:04 +02:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-26 12:06:54 +02:00
kernel bpf: Fix possible out of bound write in narrow load handling 2024-07-05 19:12:23 +02:00
lib lib/mpi: use kcalloc in mpi_resize 2024-07-05 19:10:07 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/page_alloc: speed up the iteration of max_order 2024-07-05 19:06:11 +02:00
net ipv4: fix endianness issue in inet_rtm_getroute_build_skb() 2024-07-05 19:13:33 +02:00
samples samples: pktgen: add missing IPv6 option to pktgen scripts 2024-07-05 19:11:56 +02:00
scripts scripts/tracing: fix the bug that can't parse raw_trace_func 2024-07-05 18:52:27 +02:00
security IMA: remove the dependency on CRYPTO_MD5 2024-07-05 19:13:55 +02:00
sound ASoC: rt5682: Remove unused variable in rt5682_i2c_remove() 2024-07-05 19:13:39 +02:00
SynoBuildConf init: add dsm gpl source 2024-07-05 18:00:04 +02:00
synology init: add dsm gpl source 2024-07-05 18:00:04 +02:00
tools libbpf: Re-build libbpf.so when libbpf.map changes 2024-07-05 19:11:56 +02:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: Do not leak memory for duplicate debugfs directories 2024-07-05 18:52:31 +02:00
.clang-format init: add dsm gpl source 2024-07-05 18:00:04 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS init: add dsm gpl source 2024-07-05 18:00:04 +02:00
Makefile init: add dsm gpl source 2024-07-05 18:00:04 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.