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path: root/drivers/video/backlight/pwm_bl.c
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2020-11-04backlight: pwm_bl: Fix interpolationAlexandru Stan
The previous behavior was a little unexpected, its properties/problems: 1. It was designed to generate strictly increasing values (no repeats) 2. It had quantization errors when calculating step size. Resulting in unexpected jumps near the end of some segments. Example settings: brightness-levels = <0 1 2 4 8 16 32 64 128 256>; num-interpolated-steps = <16>; Whenever num-interpolated-steps was larger than the distance between 2 consecutive brightness levels the table would get really discontinuous. The slope of the interpolation would stick with integers only and if it was 0 the whole line segment would get skipped. The distances between 1 2 4 and 8 would be 1 (property #1 fighting us), and only starting with 16 it would start to interpolate properly. Property #1 is not enough. The goal here is more than just monotonically increasing. We should still care about the shape of the curve. Repeated points might be desired if we're in the part of the curve where we want to go slow (aka slope near 0). Problem #2 is plainly a bug. Imagine if the 64 entry was 63 instead, the calculated slope on the 32-63 segment will be almost half as it should be. The most expected and simplest algorithm for interpolation is linear interpolation, which would handle both problems. Let's just implement that! Take pairs of points from the brightness-levels array and linearly interpolate between them. On the X axis (what userspace sees) we'll now have equally sized intervals (num-interpolated-steps sized, as opposed to before where we were at the mercy of quantization). Signed-off-by: Alexandru Stan <amstan@chromium.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2020-08-14Merge tag 'pwm/for-5.9-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm Pull pwm updates from Thierry Reding: "The majority of this batch is conversion of the PWM period and duty cycle to 64-bit unsigned integers, which is required so that some types of hardware can generate the full range of signals that they're capable of. The remainder is mostly minor fixes and cleanups" * tag 'pwm/for-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: pwm: bcm-iproc: handle clk_get_rate() return pwm: Replace HTTP links with HTTPS ones pwm: omap-dmtimer: Repair pwm_omap_dmtimer_chip's broken kerneldoc header pwm: mediatek: Provide missing kerneldoc description for 'soc' arg pwm: bcm-kona: Remove impossible comparison when validating duty cycle pwm: bcm-iproc: Remove impossible comparison when validating duty cycle pwm: iqs620a: Use lowercase hexadecimal literals for consistency pwm: Convert period and duty cycle to u64 clk: pwm: Use 64-bit division function backlight: pwm_bl: Use 64-bit division function pwm: sun4i: Use nsecs_to_jiffies to avoid a division pwm: sifive: Use 64-bit division macro pwm: iqs620a: Use 64-bit division pwm: imx27: Use 64-bit division macro pwm: imx-tpm: Use 64-bit division macro pwm: clps711x: Use 64-bit division macro hwmon: pwm-fan: Use 64-bit division macro drm/i915: Use 64-bit division macro
2020-07-20backlight: Use backlight_get_brightness() throughoutSam Ravnborg
Introduce the backlight_get_brightness() helper in all video/backlight/* drivers. This simplifies the code and align the implementation of the update_status() operation across the different backlight drivers. Some of the drivers gains a little extra functionality by the change as they now respect the fb_blank() ioctl. Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2020-06-17backlight: pwm_bl: Use 64-bit division functionGuru Das Srinagesh
Since the PWM framework is switching struct pwm_state.period's datatype to u64, prepare for this transition by using div_u64 to handle a 64-bit dividend instead of a straight division operation. Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Lee Jones <lee.jones@linaro.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2020-03-18backlight: pwm_bl: Switch to full GPIO descriptorLinus Walleij
The PWM backlight still supports passing a enable GPIO line as platform data using the legacy <linux/gpio.h> API. It turns out that ever board using this mechanism except one is pass .enable_gpio = -1. So we drop all these cargo-culted -1's from all instances of this platform data in the kernel. The remaning board, Palm TC, is converted to pass a machine descriptior table with the "enable" GPIO instead, and delete the platform data entry for enable_gpio and the code handling it and things should work smoothly with the new API. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Robert Jarzmik <robert.jarzmik@free.fr> Acked-by: Krzysztof Kozlowski <krzk@kernel.org Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-10-14backlight: pwm_bl: Switch to power-of-2 base for fixed-point mathRasmus Villemoes
Using a power-of-2 instead of power-of-10 base makes the computations much cheaper. 2^16 is safe; retval never becomes more than 2^48 + 2^32/2. On a 32 bit platform, the very expensive 64/32 division at the end of cie1931() instead becomes essentially free (a shift by 32 is just a register rename). Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-10-14backlight: pwm_bl: Drop use of int_pow()Rasmus Villemoes
For a fixed small exponent of 3, it is more efficient to simply use two explicit multiplications rather than calling the int_pow() library function: Aside from the function call overhead, its implementation using repeated squaring means it ends up doing four 64x64 multiplications. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-10-14backlight: pwm_bl: Eliminate a 64/32 divisionRasmus Villemoes
lightness*1000 is nowhere near overflowing 32 bits, so we can just use an ordinary 32/32 division, which is much cheaper than the 64/32 done via do_div(). Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-10-14backlight: pwm_bl: Fix cie1913 comments and constantRasmus Villemoes
The "break-even" point for the two formulas is L==8, which is also what the code actually implements. [Incidentally, at that point one has Y=0.008856, not 0.08856]. Moreover, all the sources I can find say the linear factor is 903.3 rather than 902.3, which makes sense since then the formulas agree at L==8, both yielding the 0.008856 figure to four significant digits. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-10-14backlight: pwm_bl: Add missing curly branches in else branchMatthias Kaehlcke
Add curly braces to an 'else' branch in pwm_backlight_update_status() to match the corresponding 'if' branch. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-10-14backlight: pwm_bl: Don't assign levels table repeatedlyMatthias Kaehlcke
pwm_backlight_probe() re-assigns pb->levels for every brightness level. This is not needed and was likely not intended, since neither side of the assignment changes during the loop. Assign the field only once. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-09-02backlight: pwm_bl: Set scale type for brightness curves specified in the DTMatthias Kaehlcke
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 <mka@chromium.org> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-09-02backlight: pwm_bl: Set scale type for CIE 1931 curvesMatthias Kaehlcke
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 <mka@chromium.org> Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-07-16Merge tag 'backlight-next-5.3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight Pull backlight updates from Lee Jones: "New Functionality: - Provide support for ACPI enumeration; gpio_backlight Fix-ups: - SPDX fixups; pwm_bl - Fix linear brightness levels to include number available; pwm_bl" * tag 'backlight-next-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight: backlight: pwm_bl: Fix heuristic to determine number of brightness levels backlight: gpio_backlight: Enable ACPI enumeration backlight: pwm_bl: Convert to use SPDX identifier
2019-06-27backlight: pwm_bl: Fix heuristic to determine number of brightness levelsMatthias Kaehlcke
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 <mka@chromium.org> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-06-27backlight: pwm_bl: Convert to use SPDX identifierAndy Shevchenko
Reduce size of duplicated comments by switching to use SPDX identifier. No functional change. While here, correct MODULE_LICENSE() string to be aligned with license text. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2019-06-19treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500Thomas Gleixner
Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Enrico Weigelt <info@metux.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-14lib/math: move int_pow() from pwm_bl.c for wider useAndy Shevchenko
The integer exponentiation is used in few places and might be used in the future by other call sites. Move it to wider use. Link: http://lkml.kernel.org/r/20190323172531.80025-2-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: Lee Jones <lee.jones@linaro.org> Cc: Ray Jui <rjui@broadcom.com> Cc: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-30backlight: pwm_bl: Use gpiod_get_value_cansleep() to get initial stateChen-Yu Tsai
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 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 <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>
2019-01-15Merge tag 'backlight-next-4.21' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight Pull backlight updates from Lee Jones: "Fix-ups: - Use new of_node_name_eq() API call Bug Fixes: - Internally track 'enabled' state in pwm_bl - Fix auto-generated pwm_bl brightness tables parsed by DT * tag 'backlight-next-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight: backlight: 88pm860x_bl: Use of_node_name_eq for node name comparisons backlight: pwm_bl: Fix devicetree parsing with auto-generated brightness tables backlight: pwm_bl: Re-add driver internal enabled tracking
2018-12-10backlight: pwm_bl: Fix brightness levels for non-DT case.Enric Balletbo i Serra
Commit '88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")' allows the possibility to compute a default brightness table when there isn't the brightness-levels property in the DT. Unfortunately the changes made broke the pwm backlight for the non-DT boards. Usually, the non-DT boards don't pass the brightness levels via platform data, instead, it sets the max_brightness in their platform data and the driver calculates the level without a table. The offending patch assumed that when there is no brightness levels table we should create one, but this is clearly wrong for the non-DT case. After this patch the code handles the DT and the non-DT case taking in consideration also if max_brightness is set or not. Fixes: 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye") Reported-by: Robert Jarzmik <robert.jarzmik@free.fr> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-11-27backlight: pwm_bl: Fix devicetree parsing with auto-generated brightness tablesHeiko Stuebner
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 <heiko.stuebner@bq.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-11-27backlight: pwm_bl: Re-add driver internal enabled trackingHeiko Stuebner
Commit e6bcca0890b9 ("backlight: pwm_bl: Switch to using "atomic" PWM API") removed the driver internal enabled tracking in favor of simply checking the pwm state. This can lead to issues as all of gpio-, regulator- and pwm-state are used to determine the initial state and the bootloader or kernel can leave them in an inconsistent state at boot. In my case on rk3399-kevin, the pwm backlight is build as module and the kernel disables the supply regulator as unused while keeping the pwm running thus pwm_bl calling pwm_backlight_power_off() during probe and creating an unmatched regulator-disable call, as it never got enabled from the pwm-bl before. To prevent these consistency issues, reintroduce the driver-internal tracking of the enabled state. Fixes: e6bcca0890b9 ("backlight: pwm_bl: Switch to using "atomic" PWM API") Signed-off-by: Heiko Stuebner <heiko@sntech.de> Acked-by: Thierry Reding <thierry.reding@gmail.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-10-09backlight: pwm_bl: Switch to using "atomic" PWM APIEnric Balletbo i Serra
The "atomic" API allows us to configure PWM period and duty_cycle and enable it in one call. The patch also moves the pwm_init_state just before any use of the pwm_state struct, this fixes a potential bug where pwm_get_state can be called before pwm_init_state. Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Tested-by: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-07-25backlight: pwm_bl: Fix uninitialized variableDaniel Thompson
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 <marcel.ziswiler@toradex.com> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-07-04backlight: pwm_bl: Compute brightness of LED linearly to human eyeEnric Balletbo i Serra
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 <enric.balletbo@collabora.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-07-04backlight: pwm_bl: Linear interpolation between brightness-levelsEnric Balletbo i Serra
Setting num-interpolated-steps in the dts will allow you to have linear interpolation between values of brightness-levels. This way a high resolution pwm duty cycle can be used without having to list out every possible value in the dts. This system also allows for gamma corrected values. The most simple example is interpolate between two brightness values a number of steps, this can be done setting the following in the dts: brightness-levels = <0 65535>; num-interpolated-steps = <1024>; default-brightness-level = <512>; This will create a brightness-level table with the following values: <0 63 126 189 252 315 378 441 ... 64260 64323 64386 64449 65535> Another use case can be describe a gamma corrected curve, as we have better sensitivity at low luminance than high luminance we probably want have smaller steps for low brightness levels values and bigger steps for high brightness levels values. This can be achieved with the following in the dts: brightness-levels = <0 4096 65535>; num-interpolated-steps = <1024>; default-brightness-level = <512>; This will create a brightness-levels table with the following values: <0 4 8 12 16 20 ... 4096 4156 4216 4276 ... 65535> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-04-30backlight: pwm_bl: Don't use GPIOF_* with gpiod_get_directionWolfram Sang
The documentation was wrong, gpiod_get_direction() returns 0/1 instead of the GPIOF_* flags. The docs were fixed with commit 94fc73094abe47 ("gpio: correct docs about return value of gpiod_get_direction"). Now, fix this user (until a better, system-wide solution is in place). Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-04-30pwm-backlight: Add support for PWM delays proprieties.Enric Balletbo i Serra
Some panels (i.e. N116BGE-L41), in their power sequence specifications, request a delay between set the PWM signal and enable the backlight and between clear the PWM signal and disable the backlight. Add support for the new post-pwm-on-delay-ms and pwm-off-delay-ms proprieties to meet the timings. Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Jingoo Han <jingoohan1@gmail.com> Acked-by: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-04-30pwm-backlight: Enable/disable the PWM before/after LCD enable toggle.Enric Balletbo i Serra
Before this patch the enable signal was set before the PWM signal and vice-versa on power off. This sequence is wrong, at least, it is on the different panels datasheets that I checked, so I inverted the sequence to follow the specs. For reference the following panels have the mentioned sequence: - N133HSE-EA1 (Innolux) - N116BGE (Innolux) - N156BGE-L21 (Innolux) - B101EAN0 (Auo) - B101AW03 (Auo) - LTN101NT05 (Samsung) - CLAA101WA01A (Chunghwa) Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Jingoo Han <jingoohan1@gmail.com> Acked-by: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2017-10-13backlight: pwm_bl: Fix overflow conditionDerek Basehore
This fixes an overflow condition that can happen with high max brightness and period values in compute_duty_cycle. This fixes it by using a 64 bit variable for computing the duty cycle. Signed-off-by: Derek Basehore <dbasehore@chromium.org> Acked-by: Thierry Reding <thierry.reding@gmail.com> Reviewed-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2017-08-07backlight: pwm_bl: Make of_device_ids constArvind Yadav
of_device_ids are not supposed to change at runtime. All functions working with of_device_ids provided by <linux/of.h> work with const of_device_ids. So mark the non-const structs as const. Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com> Acked-by: Thierry Reding <thierry.reding@gmail.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2017-04-19backlight: pwm_bl: Fix GPIO out for unimplemented .get_direction()Geert Uytterhoeven
Commit 7613c922315e308a ("backlight: pwm_bl: Move the checks for initial power state to a separate function") not just moved some code, but made slight changes in semantics. If a gpiochip doesn't implement the optional .get_direction() callback, gpiod_get_direction always returns -EINVAL, which is never equal to GPIOF_DIR_IN, leading to the GPIO not being configured for output. To avoid this, invert the test and check for not GPIOF_DIR_OUT instead, like the original code did. This restores the display on r8a7740/armadillo. Fixes: 7613c922315e308a ("backlight: pwm_bl: Move the checks for initial power state to a separate function") Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Acked-by: Philipp Zabel <p.zabel@pengutronix.de> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
2017-01-04backlight: pwm_bl: Check the PWM state for initial backlight power statePeter Ujfalusi
If the PWM is not enabled the backlight initially should not be enabled either if we have booted with DT and there is a phandle pointing to the backlight node. The patch extends the checks to decide if we should keep the backlight off initially. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Acked-by: Philipp Zabel <p.zabel@pengutronix.de> Reviewed-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2017-01-04backlight: pwm_bl: Move the checks for initial power state to a separate ↵Peter Ujfalusi
function Move the checks to select the initial state for the backlight to a new function and document the checks we are doing. With the separate function it is going to be easier to fix or improve the initial power state configuration later and it is easier to read the code. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de> Reviewed-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2016-10-06backlight: pwm_bl: Handle gpio that can sleepMaxime Ripard
Some backlight GPIOs might be connected to some i2c based expanders whose access might sleep. Since it's not in any critical path, use the cansleep variant of the GPIO API. Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2016-05-17backlight: pwm_bl: Use pwm_get_args() where appropriateBoris Brezillon
The PWM framework has clarified the concept of reference PWM config (the platform dependent config retrieved from the DT or the PWM lookup table) and real PWM state. Use pwm_get_args() when the PWM user wants to retrieve this reference config and not the current state. This is part of the rework allowing the PWM framework to support hardware readout and expose real PWM state even when the PWM has just been requested (before the user calls pwm_config/enable/disable()). Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17backlight: pwm_bl: Remove useless call to pwm_set_period()Boris BREZILLON
The PWM period will be set when calling pwm_config. Remove this useless call to pwm_set_period(), which might mess up the internal PWM state. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Acked-by: Lee Jones <lee.jones@linaro.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-01-11backlight: pwm_bl: Free PWM requested by legacy API on error pathVladimir Zapolskiy
If pwm is requested by legacy pwm_request() and if the following backlight_device_register() call fails, add pwm_free() clean-up. Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2016-01-11backlight: pwm_bl: Fix broken PWM backlight for non-dt platformsPhilipp Zabel
Commit ee65ad0e2a9e ("backlight: pwm_bl: Avoid backlight flicker when probed from DT") tries to dereference the device of_node pointer unconditionally, causing a NULL pointer dereference on non-dt platforms. Fix it by replacing the phandle variable with a node variable and by checking that for NULL before dereferencing it. Reported-by: Robert Jarzmik <robert.jarzmik@free.fr> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> Acked-by: Thierry Reding <thierry.reding@gmail.com> Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2016-01-11backlight: pwm_bl: Avoid backlight flicker when probed from DTPhilipp Zabel
If the driver is probed from the device tree, and there is a phandle property set on it, and the enable GPIO is already configured as output, and the backlight is currently disabled, keep it disabled. If all these conditions are met, assume there will be some other driver that can enable the backlight at the appropriate time. Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com> Tested-by: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2015-10-15backlight: pwm: Reject legacy PWM request for device defined in DTVladimir Zapolskiy
Platform PWM backlight data provided by board's device tree should be complete enough to successfully request a pwm device using pwm_get() API. This change fixes a bug, when an arbitrary (first found) PWM is connected to a "pwm-backlight" compatible device, when explicit PWM device reference is not given. Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt already describes "pwms" as a required property, instead of blind selection of a potentially wrong PWM reject legacy PWM device registration request, leave legacy API only for non-dt cases. Based on initial implementation done by Dmitry Eremin-Solenikov. Reported-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Acked-by: Thierry Reding <thierry.reding@gmail.com> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2015-06-24Merge tag 'backlight-for-linus-4.2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight Pull backlight updates from Lee Jones: "Changes to existing drivers: - supply MODULE_DEVICE_TABLE() to ensure probing - constify struct; da9052_bl - enable compile test; lcd_l4f00242t03, lcd_lms283fg05, backlight_gpio - suspend/resume bugfix; lp855x_bl - devm_gpiod_get_optional() API fixup; pwm_bl - error handling fixup; backlight" * tag 'backlight-for-linus-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight: backlight: Change the return type of backlight_update_status() to int backlight: pwm_bl: Simplify usage of devm_gpiod_get_optional backlight: lp855x: Don't clear level on suspend/blank backlight: Allow compile test of GPIO consumers if !GPIOLIB video: backlight: da9052: Constify platform_device_id gpio-backlight: Discover driver during boot time
2015-06-23backlight: pwm_bl: Simplify usage of devm_gpiod_get_optionalAxel Lin
Since 39b2bbe3d715 (gpio: add flags argument to gpiod_get*() functions), the gpiod_get* functions take an additional parameter that allows to specify direction and initial value for output. Simplify the usage of devm_gpiod_get_optional accordingly. Signed-off-by: Axel Lin <axel.lin@ingics.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2015-05-26backlight: pwm: Handle EPROBE_DEFER while requesting the PWMNicolas Ferre
When trying to request the PWM device with devm_pwm_get(), the EPROBE_DEFER flag is not handled properly. It can lead to the PWM not being found. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com> Acked-by: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2014-11-10backlight: pwm: Clean-up pwm requested using legacy APIVladimir Zapolskiy
If PWM device is requested by means of legacy API pwm_request(), its resources are not freed on module unbind, which may cause an oops on access, e.g. by reading /sys/kernel/debug/pwm. Reported-by: Dmitry Eremin-Solenikov <dmitry_eremin@mentor.com> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2014-10-11Merge tag 'backlight-for-linus-3.18' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight Pull backlight driver updates from Lee Jones: "Changes to existing drivers: - Checkpatch fixes - Removal of unused code in generic_bl - Removal of superfluous .owner attribute No new or removed drivers/supported devices" * tag 'backlight-for-linus-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight: backlight: omap1: add blank line after declarations backlight: jornada720: Remove 'else' after a return backlight: jornada720: Remove 'else' after a return backlight: wm831x_bl: Add blank line after declarations backlight: tdo24m: Add blank line after declarations backlight: s6e63m0: Remove 'else' after a return backlight: pcf50633: Add blank line after declarations backlight: lp855x: Add blank line after declarations backlight: lms501kf03: Remove 'else' after a return backlight: lm3639: Remove unnecessary return statements backlight: ld9040: Remove 'else' after a return backlight: ili922x: Remove 'else' after a return backlight: cr_bllcd: Add blank line after declarations backlight: corgi_lcd: Add blank line after declarations backlight: ams369fg06: Remove 'else' after a return backlight: adp8870: Add blank line after declarations backlight: adp8860: Add blank line after declarations backlight: adp5520: Add blank line after declarations backlight: generic_bl: Remove unused function backlight: Remove .owner field for drivers using module_platform_driver
2014-08-28backlight: Remove .owner field for drivers using module_platform_driverPeter Griffin
This patch removes the superflous .owner field for drivers which use the module_platform_driver or platform_driver_register api, as this is overriden in __platform_driver_register. Signed-off-by: Peter Griffin <peter.griffin@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2014-08-20pwm-backlight: Fix bogus request for GPIO#0 when instantiated from DTLothar Waßmann
commit 257462dbf3ed ("pwm-backlight: switch to gpiod interface") introduced a regression leading to acquiring a bogus GPIO-0 when configured from DT without an 'enable-gpios' property. The driver will happily accept the 0 initialized 'enable_gpio' member of the struct platform_pwm_backlight_data as valid gpio number, and request this GPIO as enable pin. In case of multiple driver instances, the second will fail to register with the error message: pwm-backlight backlight1.23: failed to request GPIO#0: -16 Fix this by setting enable_gpio in the pdata struct to -EINVAL. Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de> Acked-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2014-07-18backlight: pwm-backlight: Use devm_gpiod_get_optional()Alexandre Courbot
Make use of the new devm_gpiod_get_optional() to simplify the probe code. Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-16 16:47:47 +0000