On Thu, 2013-07-25 at 15:00 +0200, Rafael J. Wysocki wrote: > On Monday, July 22, 2013 09:54:21 PM Rafael J. Wysocki wrote: > > On Monday, July 22, 2013 11:11:54 AM Linus Torvalds wrote: > > > On Mon, Jul 22, 2013 at 6:02 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > > > > > > > Linus, do you want me to send a pull request reverting 8c5bd7a and efaa14c? > > > > > > Yes, but let's wait a while. Not because I think we'll fix the problem > > > (hey, miracles might happen), but because I think it would be useful > > > to couple the reverts with information about the particular machines > > > that broke (and the people who reported it). So that when we > > > inevitably try again, we can perhaps get some testing effort with > > > those machines/people. > > > > > > It doesn't seem to be a show-stopped for a large number of people, so > > > there's no huge hurry. I'd suggest doing the revert just in time for > > > rc3, but waiting until then to gather info about people who see > > > breakage. > > > > > > Sound like a plan? > > > > Yes, it does. > > OK, time to revert I guess. > > James, Kamal, Steven, Jörg, Martin, Kalle, please check if the apppended patch > fixes the backlight for you. > > Aaron, please double check if acpi_video_backlight_quirks() will still work as > needed. > > Thanks, > Rafael > > > --- > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > Subject: Revert "ACPI / video / i915: No ACPI backlight if firmware expects Windows 8" > > We attempted to address a regression introduced by commit a57f7f9 > (ACPICA: Add Windows8/Server2012 string for _OSI method.) after which > ACPI video backlight support doesn't work on a number of systems, > because the relevant AML methods in the ACPI tables in their BIOSes > become useless after the BIOS has been told that the OS is compatible > with Windows 8. That problem is tracked by the bug entry at: > > https://bugzilla.kernel.org/show_bug.cgi?id=51231 > > Commit 8c5bd7a (ACPI / video / i915: No ACPI backlight if firmware > expects Windows 8) introduced for this purpose essentially prevented > the ACPI backlight support from being used if the BIOS had been told > that the OS was compatible with Windows 8 and the i915 driver was > loaded, in which case the backlight would always be handled by i915. > Unfortunately, however, that turned out to cause problems with > backlight to appear on multiple systems with symptoms indicating that > i915 was unable to control the backlight on those systems as > expected. > > For this reason, revert commit 8c5bd7a, but leave the function > acpi_video_backlight_quirks() introduced by it, because another > commit on top of it uses that function. > Works fine for me. Tested-by: Steven Newbury <steve@xxxxxxxxxxxxxxx> By the way, I'm willing to test any i915 backlight patches if it helps. -- 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
