backlight.h documents "struct backlight_ops->get_brightness()" to return
a negative errno on failure.
So far these errors have not been handled in the backlight core.
This leads to negative values being exposed through sysfs although only
positive values are documented to be reported.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
The note in c2adda27d2 ("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 ec665b756e ("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: c2adda27d2 ("video: backlight: Add of_find_backlight helper in backlight.c")
Cc: <stable@vger.kernel.org> # 5.4+
Cc: <stable@vger.kernel.org> # 4.19.x: ec665b756e: backlight: gpio-backlight: Correct initial power state handling
Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
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>
Remove interrupt disablement during backlight setting. It is
way to dangerous and makes platforms instable by having it
miss vblank IRQs leading to the graphics derailing.
The code is using ndelay() which is not available on
platforms such as ARM and will result in 32 * udelay(1)
which is substantial.
Add some code to detect if an interrupt occurs during the
tight loop and in that case just redo it from the top.
Fixes: 5317f37e48 ("backlight: Add Kinetic KTD253 backlight driver")
Cc: Stephan Gerhold <stephan@gerhold.net>
Reported-by: newbyte@disroot.org
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
The practical upside here is that this only needs a single API call to
program the hardware which (depending on the underlaying hardware) can
be more effective and prevents glitches.
Up to now the return value of the pwm functions was ignored. Fix this
and propagate the error to the caller.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
According to <linux/backlight.h> .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 <u.kleine-koenig@pengutronix.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
With gcc-11, we get a warning about code that looks correct
but badly indented:
drivers/video/backlight/jornada720_bl.c: In function ‘jornada_bl_update_status’:
drivers/video/backlight/jornada720_bl.c:66:11: error: this ‘else’ clause does not guard... [-Werror=misleading-indentation]
66 | } else /* turn on backlight */
| ^~~~
Change the formatting according to our normal conventions.
Fixes: 13a7b5dc0d ("backlight: Adds HP Jornada 700 series backlight driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
As per the current implementation, after FSC (Full Scale Current)
and brightness update the sync bits are set-then-cleared.
But, the FSC and brightness sync takes place when the sync bits are
set (e.g. on a rising edge). So the hardware team recommends a
clear-then-set approach in order to guarantee such a transition
regardless of the previous register state.
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Currently, for WLED5, the FSC (Full scale current) setting is not
updated properly due to driver toggling the wrong register after
an FSC update.
On WLED5 we should only toggle the MOD_SYNC bit after a brightness
update. For an FSC update we need to toggle the SYNC bits instead.
Fix it by adopting the common wled3_sync_toggle() for WLED5 and
introducing new code to the brightness update path to compensate.
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
WLED3_SINK_REG_SYNC is, as the name implies, a sink register offset.
Therefore, use the sink address as base instead of the ctrl address.
This fixes the sync toggle on wled4, which can be observed by the fact
that adjusting brightness now works.
It has no effect on wled3 because sink and ctrl base addresses are the
same. This allows adjusting the brightness without having to disable
then reenable the module.
Signed-off-by: Obeida Shamoun <oshmoun100@googlemail.com>
Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Kiran Gunda <kgunda@codeaurora.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Pull ARM updates from Russell King:
- Generalise byte swapping assembly
- Update debug addresses for STI
- Validate start of physical memory with DTB
- Do not clear SCTLR.nTLSMD in decompressor
- amba/locomo/sa1111 devices remove method return type is void
- address markers for KASAN in page table dump
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: 9065/1: OABI compat: fix build when EPOLL is not enabled
ARM: 9055/1: mailbox: arm_mhuv2: make remove callback return void
amba: Make use of bus_type functions
amba: Make the remove callback return void
vfio: platform: simplify device removal
amba: reorder functions
amba: Fix resource leak for drivers without .remove
ARM: 9054/1: arch/arm/mm/mmu.c: Remove duplicate header
ARM: 9053/1: arm/mm/ptdump:Add address markers for KASAN regions
ARM: 9051/1: vdso: remove unneded extra-y addition
ARM: 9050/1: Kconfig: Select ARCH_HAVE_NMI_SAFE_CMPXCHG where possible
ARM: 9049/1: locomo: make locomo bus's remove callback return void
ARM: 9048/1: sa1111: make sa1111 bus's remove callback return void
ARM: 9047/1: smp: remove unused variable
ARM: 9046/1: decompressor: Do not clear SCTLR.nTLSMD for ARMv7+ cores
ARM: 9045/1: uncompress: Validate start of physical memory against passed DTB
ARM: 9042/1: debug: no uncompress debugging while semihosting
ARM: 9041/1: sti LL_UART: add STiH418 SBC UART0 support
ARM: 9040/1: use DEBUG_UART_PHYS and DEBUG_UART_VIRT for sti LL_UART
ARM: 9039/1: assembler: generalize byte swapping macro into rev_l
The KTD253 backlight might already be on when the driver
is probed: then we don't really know what the current
ratio is and all light intensity settings will be off
relative to what it was at boot.
To fix this, bring up the backlight OFF then move it to
the default backlight from there so we know the state.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This converts the lms283gf05 backlight driver to use GPIO
descriptors and switches the single PXA Palm Z2 device
over to defining these.
Since the platform data was only used to convey GPIO
information we can delete the platform data header.
Notice that we define the proper active low semantics in
the board file GPIO descriptor table (active low) and
assert the reset line by bringing it to "1" (asserted).
Cc: Marek Vasut <marex@denx.de>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Mack <daniel@zonque.org>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
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>
Pull backlight updates from Lee Jones:
"New Drivers:
- Add support for KTD253
Fix-ups:
- Add Device Tree documentation; common, kinetic,ktd253
- Use correct header(s); tosa_lcd, tosa_bl
Bug Fixes:
- Fix refcount imbalance; sky81452-backlight"
* tag 'backlight-next-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
backlight: tosa_bl: Include the right header
backlight: tosa_lcd: Include the right header
backlight: Add Kinetic KTD253 backlight driver
dt-bindings: backlight: Add Kinetic KTD253 bindings
dt-bindings: backlight: Add some common backlight properties
backlight: sky81452-backlight: Fix refcount imbalance on error
