linux-stable.git/drivers/video/backlight, branch v5.4.166

video: backlight: Drop maximum brightness override for brightness zero

2021-11-17T08:48:50+00:00

commit 33a5471f8da976bf271a1ebbd6b9d163cb0cb6aa upstream.

The note in c2adda27d202f ("video: backlight: Add of_find_backlight helper
in backlight.c") says that gpio-backlight uses brightness as power state.
This has been fixed since in ec665b756e6f7 ("backlight: gpio-backlight:
Correct initial power state handling") and other backlight drivers do not
require this workaround. Drop the workaround.

This fixes the case where e.g. pwm-backlight can perfectly well be set to
brightness 0 on boot in DT, which without this patch leads to the display
brightness to be max instead of off.

Fixes: c2adda27d202f ("video: backlight: Add of_find_backlight helper in backlight.c")
Cc:  # 5.4+
Cc:  # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
Signed-off-by: Marek Vasut 
Acked-by: Noralf Trønnes 
Reviewed-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Greg Kroah-Hartman

backlight: pwm_bl: Improve bootloader/kernel device handover

2021-09-15T07:47:41+00:00

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 
Signed-off-by: Daniel Thompson 
Acked-by: Marek Vasut 
Tested-by: Marek Vasut 
Signed-off-by: Lee Jones 
Signed-off-by: Greg Kroah-Hartman

backlight: lm3630a: Fix return code of .update_status() callback

2021-07-20T14:10:45+00:00

[ Upstream commit b9481a667a90ec739995e85f91f3672ca44d6ffa ]

According to  .update_status() is supposed to
return 0 on success and a negative error code otherwise. Adapt
lm3630a_bank_a_update_status() and lm3630a_bank_b_update_status() to
actually do it.

While touching that also add the error code to the failure message.

Signed-off-by: Uwe Kleine-König 
Reviewed-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: lm3630a_bl: Put fwnode in error case during ->probe()

2021-07-14T14:53:40+00:00

[ Upstream commit 6d1c32dbedd7d7e7372aa38033ec8782c39f6379 ]

device_for_each_child_node() bumps a reference counting of a returned variable.
We have to balance it whenever we return to the caller.

Cc: Brian Masney 
Cc: Dan Murphy 
Fixes: 8fbce8efe15cd ("backlight: lm3630a: Add firmware node support")
Signed-off-by: Andy Shevchenko 
Reviewed-by: Brian Masney 
Reviewed-by: Daniel Thompson 
Signed-off-by: Lee Jones 
Signed-off-by: Sasha Levin

backlight: sky81452-backlight: Fix refcount imbalance on error

2020-10-29T08:57:37+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

2020-06-24T15:50:09+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

Merge tag 'backlight-next-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight

2019-09-24T02:33:56+00:00

Pull backlight updates from Lee Jones:
 "Core Frameworks
   - Obtain scale type through sysfs

  New Functionality:
   - Provide Device Tree functionality in rave-sp-backlight
   - Calculate if scale type is (non-)linear in pwm_bl

  Fix-ups:
   - Simplify code in lm3630a_bl
   - Trivial rename/whitespace/typo fixes in lms283gf05
   - Remove superfluous NULL check in tosa_lcd
   - Fix power state initialisation in gpio_backlight
   - List supported file in MAINTAINERS

  Bug Fixes:
   - Kconfig - default to not building unless requested in
     {LED,BACKLIGHT}_CLASS_DEVICE"

* tag 'backlight-next-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  backlight: pwm_bl: Set scale type for brightness curves specified in the DT
  backlight: pwm_bl: Set scale type for CIE 1931 curves
  backlight: Expose brightness curve type through sysfs
  MAINTAINERS: Add entry for stable backlight sysfs ABI documentation
  backlight: gpio-backlight: Correct initial power state handling
  video: backlight: tosa_lcd: drop check because i2c_unregister_device() is NULL safe
  video: backlight: Drop default m for {LCD,BACKLIGHT_CLASS_DEVICE}
  backlight: lms283gf05: Fix a typo in the description passed to 'devm_gpio_request_one()'
  backlight: lm3630a: Switch to use fwnode_property_count_uXX()
  backlight: rave-sp: Leave initial state and register with correct device

backlight: pwm_bl: Set scale type for brightness curves specified in the DT

2019-09-02T14:55:15+00:00

Check if a brightness curve specified in the device tree is linear or
not and set the corresponding property accordingly. This makes the
scale type available to userspace via the 'scale' sysfs attribute.

To determine if a curve is linear it is compared to a interpolated linear
curve between min and max brightness. The curve is considered linear if
no value deviates more than +/-5% of ${brightness_range} from their
interpolated value.

Signed-off-by: Matthias Kaehlcke 
Acked-by: Daniel Thompson 
Signed-off-by: Lee Jones

backlight: pwm_bl: Set scale type for CIE 1931 curves

2019-09-02T14:55:11+00:00

For backlight curves calculated with the CIE 1931 algorithm set
the brightness scale type to non-linear. This makes the scale type
available to userspace via the 'scale' sysfs attribute.

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

backlight: Expose brightness curve type through sysfs

2019-09-02T14:55:03+00:00

Backlight brightness curves can have different shapes. The two main
types are linear and non-linear curves. The human eye doesn't
perceive linearly increasing/decreasing brightness as linear (see
also 88ba95bedb79 "backlight: pwm_bl: Compute brightness of LED
linearly to human eye"), hence many backlights use non-linear (often
logarithmic) brightness curves. The type of curve currently is opaque
to userspace, so userspace often uses more or less reliable heuristics
(like the number of brightness levels) to decide whether to treat a
backlight device as linear or non-linear.

Export the type of the brightness curve via the new sysfs attribute
'scale'. The value of the attribute can be 'linear', 'non-linear' or
'unknown'. For devices that don't provide information about the scale
of their brightness curve the value of the 'scale' attribute is 'unknown'.

Signed-off-by: Matthias Kaehlcke 
Reviewed-by: Daniel Thompson 
Signed-off-by: Lee Jones