> On Fri, 22 Aug 2014, Bertrik Sikken <bertrik@xxxxxxxxx> wrote: >> On 19-8-2014 3:29, Jani Nikula wrote: >>> On Tue, 19 Aug 2014, Bertrik Sikken <bertrik@xxxxxxxxx> wrote: >>>>> On Sun, 17 Aug 2014, Bertrik Sikken <bertrik@xxxxxxxxx> wrote: >>>>>> On 15-8-2014 3:43, Jani Nikula wrote: >>>>>>> On Thu, 14 Aug 2014, Bertrik Sikken <bertrik@xxxxxxxxx> wrote: >>>>>> >>>>>>>> Attached is dmesg output from booting kernel 3.14-2 (debian >>>>>>>> unstable) >>>>>>>> with drm.debug=0xe and the samsung_laptop module enabled, from my >>>>>>>> Samsung N150plus netbook. >>>>>>> >>>>>>> Have you tried 3.15? >>>>>> >>>>>> I've built the v3.15 kernel (using the .config file from debian >>>>>> unstable and doing make oldconfig). >>>>>> >>>>>> The backlight is at maximum brightness after boot and I can't >>>>>> control >>>>>> it using the backlight buttons, nor by writing to >>>>>> /sys/class/backlight/samsung/brightness >>>>>> (say half the value or 1/10th of max_brightness) >>>>>> >>>>>> Backlight does work when writing >>>>>> /sys/class/backlight/intel_backlight/brightness >>>>> >>>>> How about disabling samsung backlight module with 3.15? >>>> >>>> I'm not sure what you mean by that. >>>> >>>> As I understand it, there are three ways to control the backlight on >>>> this >>>> netbook: using intel_backlight, samsung_laptop (using a "sabi" >>>> interface) >>>> and acpi_video. >>>> Backlight control using the samsung_laptop driver no longer seems to >>>> work >>>> after the change. If I disable it (e.g. by blacklisting it), I expect >>>> it >>>> to no longer work at all obviously. >>>> >>>> What do you want me to test exactly? >>> >>> If the intel_backlight interface works in 3.15, I presume the problem >>> is >>> that you have a non-functional samsung backlight interface that is >>> preferred over intel_backlight by your userspace. >> >> I tested the intel_backlight interface in linux v3.15 with the samsung >> backlight module blacklisted. The intel_backlight interface still works. > > I read that as, "I no longer have problems with backlight". The problem as I see it, is that the bisected backlight change in the intel-gfx driver caused the samsung_laptop backlight mechanism to break, while they apparently were able to play nice with each other before. You could consider having two drivers trying to access the same hardware as a more general linux kernel bug. As I understand it now, the intel-gfx driver talks directly to the hardware and the samsung_laptop driver talks through a BIOS interface (SABI = "Samsung advanced BIOS interface"). I'm not trying to put the blame on any of the two drivers, just looking for the best solution to a practical problem. With kind regards, Bertrik Sikken _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
