No backlight since linux-4.2.4 - drivers/gpu/drm/radeon/atombios_encoders.c

[Michael Burian]

On 10/27/15 10:17, Michel Dänzer wrote:
> 
> I'm not familiar with the ATOM bytecode, but since the number of
> bytecode instructions executed seems the same in both cases, I suspect
> that dig->backlight_level == 0 => ATOM_LCD_BLOFF is executed. (The
> debugging output in my patch would have provided all of this information
> and more, but there wasn't any of it in the dmesg you provided)
> 
> I guess the question then becomes how dig->backlight_level is (supposed
> to be) initialized.
> 
> What values do the following files contain in the broken and working cases?
> 
> /sys/class/backlight/radeon_bl0/bl_power
> /sys/class/backlight/radeon_bl0/brightness
> /sys/class/backlight/radeon_bl0/actual_brightness
> /sys/class/backlight/radeon_bl0/max_brightness
> 
> 

These files do not exist on my system,
I can offer /sys/class/backlight/acpi_video0/

content is identical in both cases

bl_power        0
brightness      10
actual_brightness       10
max_brightness  10