Hi,
On Sat, 23 Oct 2021 at 03:23, Dario Binacchi dariobin@libero.it wrote:
Hi Guillaume,
Il 22/10/2021 14:34 Guillaume GARDET guillaume.gardet@free.fr ha scritto:
Hi Dario,
----- Dario Binacchi dariobin@libero.it a écrit :
Hi Guillaume,
Il 21/10/2021 16:47 Guillaume GARDET guillaume.gardet@free.fr ha scritto:
Hi,
Commit 76c2ff3e [0] broke backlight on Chromebook snow. A revert on top of 2021.10 restores the backlight. Not sure why it breaks on Chromebook snow yet. Dario, any idea how to fix this?
Is it possible that max_level is equal to min_level and therefore division by zero is done?
I do not think so, because u-boot does not crash and the DTS file has multiple levels: https://source.denx.de/u-boot/u-boot/-/blob/master/arch/arm/dts/exynos5250-s...
I think the problem occurs when 'cur_level == max_level', which is also the default value in the DTS. If I change the default-brightness-level to 6 (instead of 7), then the backlight works again, which would confirm the assumption above.
I have set the default-brightness-level to max-level on my beaglebone board but the backlight works the same. I didn't see any difference.
I got this running in my lab now and sent a possible fix.
Regards, Simon
Thanks and regards Dario
pwm_backlight_set_brightness seems to set cur_level to max value by default. Maybe the driver thinks there is nothing to do, since current level is also the desired level?
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