Hi, On Sat, 23 Oct 2021 at 03:23, Dario Binacchi <dario...@libero.it> wrote: > > Hi Guillaume, > > > Il 22/10/2021 14:34 Guillaume GARDET <guillaume.gar...@free.fr> ha scritto: > > > > > > Hi Dario, > > > > ----- Dario Binacchi <dario...@libero.it> a écrit : > > > Hi Guillaume, > > > > > > > Il 21/10/2021 16:47 Guillaume GARDET <guillaume.gar...@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-snow.dts#L243 > > > > 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? [..]
