Hi, On 07/22/2014 08:52 AM, Daniel Vetter wrote: > On Tue, Jul 22, 2014 at 8:42 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: >> Hi Jani et al, >> >> A friend of mine Bertrik Sikken (in the Cc) his backlight control >> stopped working for him on his Samsung N150Plus netbook. >> >> I took a quick look, and the raw intel_backlight backlight interface >> works under 3.14, but the firmware samsung_laptop backlight interface, >> which is what most userspace apps will use by default, stops working >> in 3.14 . >> >> I've asked him to bisect this and the bisect points out this >> commit as the culprit: >> >> b35684b8fa94e04f55fd38bf672b737741d2f9e2 is the first bad commit >> commit b35684b8fa94e04f55fd38bf672b737741d2f9e2 >> Author: Jani Nikula <jani.nikula@xxxxxxxxx> >> Date: Thu Nov 14 12:13:41 2013 +0200 >> >> drm/i915: do full backlight setup at enable time >> >> We should now have all the information we need to do a full >> initialization of the backlight registers. >> >> v2: Keep QUIRK_NO_PCH_PWM_ENABLE for now (Imre). >> >> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> >> Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx> >> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> >> >> Note that this laptop has an acpi_video backlight interface too, >> but that has been broken from the start and gets disabled by >> samsung-laptop based on dmi matching. > > How does the intel backlight fare? That works fine with 3.14 . > Please test both 3.14 and 3.15 and We've tested with 3.14, please let us know if you also want Bertrik to test with 3.15. > also test what happens when you blacklist the samsung-laptop driver > (if that's possible without wreaking the machine). Then the vendor interface won't get promoted, acpi-video will load, and things likely will not work. Bertrik, can you try blacklisting the samsung-laptop module, then check /sys/class/backlight, the samsung_laptop dir should be gone replaced by an acpi_video0 (or some such) dir. Please try if that works. If that does not work, try booting with both the module blacklisted and "acpi_backlight=vendor" on the kernel commandline, then you should see only the intel-backlight under /sys/class/backlight and things should work. > Also please grab latest intel-gpu-tools and record a register dump > with intel_reg_dump, again for both broken and working kernels. Bertrik, can you do this please (without the blacklisting or special kernel commandline options). Regards, Hans _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
