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Chen-Yu Tsai cec2b18832 backlight: pwm_bl: Use gpiod_get_value_cansleep() to get initial state 
gpiod_get_value() gives out a warning if access to the underlying gpiochip
requires sleeping, which is common for I2C based chips:

    WARNING: CPU: 0 PID: 77 at drivers/gpio/gpiolib.c:2500 gpiod_get_value+0xd0/0x100
    Modules linked in:
    CPU: 0 PID: 77 Comm: kworker/0:2 Not tainted 4.14.0-rc3-00589-gf32897915d48-dirty #90
    Hardware name: Allwinner sun4i/sun5i Families
    Workqueue: events deferred_probe_work_func
    [<c010ec50>] (unwind_backtrace) from [<c010b784>] (show_stack+0x10/0x14)
    [<c010b784>] (show_stack) from [<c0797224>] (dump_stack+0x88/0x9c)
    [<c0797224>] (dump_stack) from [<c0125b08>] (__warn+0xe8/0x100)
    [<c0125b08>] (__warn) from [<c0125bd0>] (warn_slowpath_null+0x20/0x28)
    [<c0125bd0>] (warn_slowpath_null) from [<c037069c>] (gpiod_get_value+0xd0/0x100)
    [<c037069c>] (gpiod_get_value) from [<c03778d0>] (pwm_backlight_probe+0x238/0x508)
    [<c03778d0>] (pwm_backlight_probe) from [<c0411a2c>] (platform_drv_probe+0x50/0xac)
    [<c0411a2c>] (platform_drv_probe) from [<c0410224>] (driver_probe_device+0x238/0x2e8)
    [<c0410224>] (driver_probe_device) from [<c040e820>] (bus_for_each_drv+0x44/0x94)
    [<c040e820>] (bus_for_each_drv) from [<c040ff0c>] (__device_attach+0xb0/0x114)
    [<c040ff0c>] (__device_attach) from [<c040f4f8>] (bus_probe_device+0x84/0x8c)
    [<c040f4f8>] (bus_probe_device) from [<c040f944>] (deferred_probe_work_func+0x50/0x14c)
    [<c040f944>] (deferred_probe_work_func) from [<c013be84>] (process_one_work+0x1ec/0x414)
    [<c013be84>] (process_one_work) from [<c013ce5c>] (worker_thread+0x2b0/0x5a0)
    [<c013ce5c>] (worker_thread) from [<c0141908>] (kthread+0x14c/0x154)
    [<c0141908>] (kthread) from [<c0107ab0>] (ret_from_fork+0x14/0x24)

This was missed in commit 0c9501f823 ("backlight: pwm_bl: Handle gpio
that can sleep"). The code was then moved to a separate function in
commit 7613c92231 ("backlight: pwm_bl: Move the checks for initial power
state to a separate function").

The only usage of gpiod_get_value() is during the probe stage, which is
safe to sleep in. Switch to gpiod_get_value_cansleep().

Fixes: 0c9501f823 ("backlight: pwm_bl: Handle gpio that can sleep")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-01-30 13:37:42 +00:00
arch x86: uaccess: Inhibit speculation past access_ok() in user_access_begin() 2019-01-20 15:33:22 +12:00
block block: Cleanup license notice 2019-01-17 21:21:40 -07:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto crypto: sm3 - fix undefined shift by >= width of value 2019-01-10 21:37:32 +08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-21 12:52:31 +13:00
drivers backlight: pwm_bl: Use gpiod_get_value_cansleep() to get initial state 2019-01-30 13:37:42 +00:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs Fixes for pstore/ram 2019-01-21 13:12:03 +13:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-21 12:52:31 +13:00
init kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7 2019-01-14 10:37:09 +09:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-21 12:52:31 +13:00
lib fix int_sqrt64() for very large numbers 2019-01-21 07:20:18 +13:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
mm mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one 2019-01-10 02:58:21 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-21 12:52:31 +13:00
samples samples/bpf: workaround clang asm goto compilation errors 2019-01-15 20:57:30 +01:00
scripts Bug fixes for gcc-plugins 2019-01-21 13:07:03 +13:00
security Merge branch 'fixes-v5.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-01-17 16:54:58 +12:00
sound remove dma_zalloc_coherent 2019-01-12 10:52:40 -08:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-21 12:52:31 +13:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt KVM: validate userspace input in kvm_clear_dirty_log_protect() 2019-01-11 18:38:07 +01:00
.clang-format clang-format: Update .clang-format with the latest for_each macro list 2019-01-19 19:26:06 +01:00
.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: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Add CREDITS entry for Shaohua Li 2019-01-04 14:27:09 -07:00
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: update email addresses of liquidio driver maintainers 2019-01-18 14:07:06 -08:00
Makefile Linux 5.0-rc3 2019-01-21 13:14:44 +13:00
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.