Re: Linux 3.11-rc2 (acpi backlight, revert)

[Kamal Mostafa <kamal@canonical.com>]

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On Thu, 2013-07-25 at 16:46 +0200, Daniel Vetter wrote:
> On Thu, Jul 25, 2013 at 07:43:17AM -0700, Kamal Mostafa wrote:
> > 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@sisk.pl> 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.
> > 
> > Yes, this revert patch does re-enable backlight control for the affected
> > Dell XPS13 models.
> 
> Are these the same models that neeed the special quirk to not write
> PCH_PWM_ENABLE? Or do they need both?

Hi Daniel-

Yes, these are the same models (Dell XPS13) that need the PCH_PWM_ENABLE
quirk, but that's not related to this ACPI problem...

All of the XPS13 models still need the PCH_PWM_ENABLE quirk which is now
present in mainline (e85843b "drm/i915: quirk no PCH_PWM_ENABLE for Dell
XPS13 backlight").

Separately from that, some of the XPS13 models were _also_ adversely
affected (as were some other machines) by the ACPI changes that are
about to be reverted.

 -Kamal


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