Am Wed, 16 Jul 2014 10:36:56 +0800 schrieb Aaron Lu <aaron.lu@xxxxxxxxx>: > On 07/15/2014 02:56 AM, Julian Wollrath wrote: > > Am Mon, 14 Jul 2014 21:10:47 +0200 > > schrieb "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>: > > > >> On Monday, July 14, 2014 09:02:34 PM Rafael J. Wysocki wrote: > >>> On Monday, July 14, 2014 08:34:22 PM Julian Wollrath wrote: > >>>> Am Mon, 14 Jul 2014 20:21:19 +0200 > >>>> schrieb "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>: > >>>> > >>>>> On Saturday, July 12, 2014 06:24:52 PM Julian Wollrath wrote: > >>>>>> Hi, > >>>>>> > >>>>>>> changing the brightness on my Thinkpad X230 with Intel > >>>>>>> HD4000 graphics, stopped working after commit 886129a8eebe > >>>>>>> (ACPI / video: change acpi-video brightness_switch_enabled > >>>>>>> default to 0). Changing it back to 1, fixes the problem, if > >>>>>>> "acpi_osi=!Windows 2012" is also set. Before that commit > >>>>>>> just setting "acpi_osi=!Windows 2012" was enough to get > >>>>>>> changing the brightness working. > >>>>>> > >>>>>> small correction: It setting "acpi_osi=!Windows 2012" does > >>>>>> only help when using a kernel with commit 886129a8eebe as > >>>>>> HEAD, with v3.16-rc4 setting > >>>>>> video.brightness_switch_enabled=1 and acpi_osi=!Windows 2012 > >>>>>> or just one of them, does not make changing the brightness > >>>>>> work again. > >>>>> > >>>>> And reverting commit 751109aad583 (ACPI / video: Change the > >>>>> default for video.use_native_backlight to 1) make that last > >>>>> problem go away, right? > >>>>> > >>>>> We are going to rever commit 886129a8eebe for other reasons, so > >>>>> can you please revert it from 3.16-rc5 on your system and > >>>>> report back? > >>>> Yes, with both 751109aad583 and 886129a8eebe reverted, changing > >>>> the brightness works again. > >>> > >>> What if you revert 886129a8eebe alone? > >> > >> I mean, what exactly do you need to pass to the kernel command line > >> in that case to make brightness switching work? > > I need to pass > > acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 > > video.use_native_backlight=-1 > > > > If I leave one of these parameters out, the brightness switch stops > > working. > > If you only pass the following 2 cmdline options: > acpi_osi="!Windows 2012" video.brightness_switch_enabled=1 > Will there be the /sys/class/backlight/acpi_videoX file? Yes, and interestingly with v3.16-rc5 the brightness switching works with just these two options. Cheers, Julian -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
