linux-stable.git/drivers/video/backlight, branch v4.19.166

backlight: sky81452-backlight: Fix refcount imbalance on error

2020-10-29T08:55:07+00:00

[ Upstream commit b7a4f80bc316a56d6ec8750e93e66f42431ed960 ]

When of_property_read_u32_array() returns an error code, a
pairing refcount decrement is needed to keep np's refcount
balanced.

Fixes: f705806c9f355 ("backlight: Add support Skyworks SKY81452 backlight driver")
Signed-off-by: Dinghao Liu 
Reviewed-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: lp855x: Ensure regulators are disabled on probe failure

2020-06-25T13:32:48+00:00

[ Upstream commit d8207c155a7c6015eb7f43739baa7dfb1fa638af ]

If probing the LP885x backlight fails after the regulators have been
enabled, then the following warning is seen when releasing the
regulators ...

 WARNING: CPU: 1 PID: 289 at drivers/regulator/core.c:2051 _regulator_put.part.28+0x158/0x160
 Modules linked in: tegra_xudc lp855x_bl(+) host1x pwm_tegra ip_tables x_tables ipv6 nf_defrag_ipv6
 CPU: 1 PID: 289 Comm: systemd-udevd Not tainted 5.6.0-rc2-next-20200224 #1
 Hardware name: NVIDIA Jetson TX1 Developer Kit (DT)

 ...

 Call trace:
  _regulator_put.part.28+0x158/0x160
  regulator_put+0x34/0x50
  devm_regulator_release+0x10/0x18
  release_nodes+0x12c/0x230
  devres_release_all+0x34/0x50
  really_probe+0x1c0/0x370
  driver_probe_device+0x58/0x100
  device_driver_attach+0x6c/0x78
  __driver_attach+0xb0/0xf0
  bus_for_each_dev+0x68/0xc8
  driver_attach+0x20/0x28
  bus_add_driver+0x160/0x1f0
  driver_register+0x60/0x110
  i2c_register_driver+0x40/0x80
  lp855x_driver_init+0x20/0x1000 [lp855x_bl]
  do_one_initcall+0x58/0x1a0
  do_init_module+0x54/0x1d0
  load_module+0x1d80/0x21c8
  __do_sys_finit_module+0xe8/0x100
  __arm64_sys_finit_module+0x18/0x20
  el0_svc_common.constprop.3+0xb0/0x168
  do_el0_svc+0x20/0x98
  el0_sync_handler+0xf4/0x1b0
  el0_sync+0x140/0x180

Fix this by ensuring that the regulators are disabled, if enabled, on
probe failure.

Finally, ensure that the vddio regulator is disabled in the driver
remove handler.

Signed-off-by: Jon Hunter 
Reviewed-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: pwm_bl: Fix heuristic to determine number of brightness levels

2020-01-27T13:50:58+00:00

[ Upstream commit 73fbfc499448455f1e1c77717040e09e25f1d976 ]

With commit 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of
LED linearly to human eye") the number of set bits (aka hweight())
in the PWM period is used in the heuristic to determine the number
of brightness levels, when the brightness table isn't specified in
the DT. The number of set bits doesn't provide a reliable clue about
the length of the period, instead change the heuristic to:

 nlevels = period / fls(period)

Also limit the maximum number of brightness levels to 4096 to avoid
excessively large tables.

With this the number of levels increases monotonically with the PWM
period, until the maximum of 4096 levels is reached:

period (ns)    # levels

100    	       16
500	       62
1000	       111
5000	       416
10000	       769
50000	       3333
100000	       4096

Fixes: 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")
Signed-off-by: Matthias Kaehlcke 
Acked-by: Daniel Thompson 
Tested-by: Enric Balletbo i Serra 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: lm3630a: Return 0 on success in update_status functions

2020-01-27T13:50:48+00:00

[ Upstream commit d3f48ec0954c6aac736ab21c34a35d7554409112 ]

lm3630a_bank_a_update_status() and lm3630a_bank_b_update_status()
both return the brightness value if the brightness was successfully
updated. Writing to these attributes via sysfs would cause a 'Bad
address' error to be returned. These functions should return 0 on
success, so let's change it to correct that error.

Fixes: 28e64a68a2ef ("backlight: lm3630: apply chip revision")
Signed-off-by: Brian Masney 
Acked-by: Pavel Machek 
Acked-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: lm3639: Unconditionally call led_classdev_unregister

2019-11-24T07:20:45+00:00

[ Upstream commit 7cea645ae9c5a54aa7904fddb2cdf250acd63a6c ]

Clang warns that the address of a pointer will always evaluated as true
in a boolean context.

drivers/video/backlight/lm3639_bl.c:403:14: warning: address of
'pchip->cdev_torch' will always evaluate to 'true'
[-Wpointer-bool-conversion]
        if (&pchip->cdev_torch)
        ~~   ~~~~~~~^~~~~~~~~~
drivers/video/backlight/lm3639_bl.c:405:14: warning: address of
'pchip->cdev_flash' will always evaluate to 'true'
[-Wpointer-bool-conversion]
        if (&pchip->cdev_flash)
        ~~   ~~~~~~~^~~~~~~~~~
2 warnings generated.

These statements have been present since 2012, introduced by
commit 0f59858d5119 ("backlight: add new lm3639 backlight
driver"). Given that they have been called unconditionally since
then presumably without any issues, removing the always true if
statements to fix the warnings without any real world changes.

Link: https://github.com/ClangBuiltLinux/linux/issues/119
Signed-off-by: Nathan Chancellor 
Reviewed-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: pwm_bl: Use gpiod_get_value_cansleep() to get initial state

2019-04-05T20:33:13+00:00

[ Upstream commit cec2b18832e26bc866bef2be22eff4e25bbc4034 ]

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
    [] (unwind_backtrace) from [] (show_stack+0x10/0x14)
    [] (show_stack) from [] (dump_stack+0x88/0x9c)
    [] (dump_stack) from [] (__warn+0xe8/0x100)
    [] (__warn) from [] (warn_slowpath_null+0x20/0x28)
    [] (warn_slowpath_null) from [] (gpiod_get_value+0xd0/0x100)
    [] (gpiod_get_value) from [] (pwm_backlight_probe+0x238/0x508)
    [] (pwm_backlight_probe) from [] (platform_drv_probe+0x50/0xac)
    [] (platform_drv_probe) from [] (driver_probe_device+0x238/0x2e8)
    [] (driver_probe_device) from [] (bus_for_each_drv+0x44/0x94)
    [] (bus_for_each_drv) from [] (__device_attach+0xb0/0x114)
    [] (__device_attach) from [] (bus_probe_device+0x84/0x8c)
    [] (bus_probe_device) from [] (deferred_probe_work_func+0x50/0x14c)
    [] (deferred_probe_work_func) from [] (process_one_work+0x1ec/0x414)
    [] (process_one_work) from [] (worker_thread+0x2b0/0x5a0)
    [] (worker_thread) from [] (kthread+0x14c/0x154)
    [] (kthread) from [] (ret_from_fork+0x14/0x24)

This was missed in commit 0c9501f823a4 ("backlight: pwm_bl: Handle gpio
that can sleep"). The code was then moved to a separate function in
commit 7613c922315e ("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: 0c9501f823a4 ("backlight: pwm_bl: Handle gpio that can sleep")
Signed-off-by: Chen-Yu Tsai 
Acked-by: Maxime Ripard 
Acked-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: pwm_bl: Fix devicetree parsing with auto-generated brightness tables

2019-02-27T09:08:50+00:00

[ Upstream commit 61170ee9386888f1e6f7e9cc58e8d9a8c2a3c1dd ]

Commit 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly
to human eye") made the parse-dt function return early when using an auto-
generated brightness-table, but didn't take into account that some more
settings were handled below the brightness handling, like power-on-delays
and also setting the pdata enable-gpio to -EINVAL.

This surfaces for example in the case of a backlight without any
enable-gpio which then tries to use gpio-0 in error.

Fix this by simply moving the trailing settings above the brightness
handling.

Fixes: 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")
Signed-off-by: Heiko Stuebner 
Acked-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: pwm_bl: Fix uninitialized variable

2018-07-25T08:09:59+00:00

Currently, if the DT does not define num-interpolated-steps then
num_steps is undefined and the interpolation code will deploy randomly.
Fix with a simple initialize to zero.

Fixes: 573fe6d1c25c ("backlight: pwm_bl: Linear interpolation between brightness-levels")
Reported-by: Marcel Ziswiler 
Signed-off-by: Daniel Thompson 
Tested-by: Marcel Ziswiler 
Reviewed-by: Douglas Anderson 
Signed-off-by: Lee Jones

backlight: adp8860: Mark expected switch fall-through

2018-07-13T07:35:15+00:00

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Signed-off-by: Gustavo A. R. Silva 
Acked-by: Michael Hennerich 
Reviewed-by: Daniel Thompson 
Signed-off-by: Lee Jones

backlight: pwm_bl: Compute brightness of LED linearly to human eye

2018-07-04T09:31:18+00:00

When you want to change the brightness using a PWM signal, one thing you
need to consider is how human perceive the brightness. Human perceive
the brightness change non-linearly, we have better sensitivity at low
luminance than high luminance, so to achieve perceived linear dimming,
the brightness must be matches to the way our eyes behave. The CIE 1931
lightness formula is what actually describes how we perceive light.

This patch computes a default table with the brightness levels filled
with the numbers provided by the CIE 1931 algorithm, the number of the
brightness levels is calculated based on the PWM resolution.

The calculation of the table using the CIE 1931 algorithm is enabled by
default when you do not define the 'brightness-levels' propriety in your
device tree.

Signed-off-by: Enric Balletbo i Serra 
Acked-by: Daniel Thompson 
Signed-off-by: Lee Jones