Re: Suspend/resume regression in Toshiba A11 since 2.6.34-rc4

[Rafael J. Wysocki]

On Monday, March 21, 2011, Herton Ronaldo Krzesinski wrote:
> On Sat, Mar 19, 2011 at 09:52:52PM +0100, Rafael J. Wysocki wrote:
> > On Saturday, March 19, 2011, Herton Ronaldo Krzesinski wrote:
> > > On Fri, Mar 18, 2011 at 11:38:52PM +0100, Rafael J. Wysocki wrote:
> > > > On Friday, March 18, 2011, Herton Ronaldo Krzesinski wrote:
> > > > > This regression is old, but discovered recently. Since 2.6.34-rc4,
> > > > > a Toshiba Tecra A11 machine resumes without video for the first time.
> > > > > Here is the strange thing reported, on the first suspend/resume, when
> > > > > the machine wakes up the video is blank, but the machine is up (just the
> > > > > screen is black). If you suspend again, on second resume the video comes
> > > > > back normally.
> > > > > 
> > > > > Helping the reporter bisecting the problem, we narrowed down the bug to
> > > > > this commit:
> > > > > 
> > > > > commit ac7729da880e742613129ee6dea0045328670d2d
> > > > > Author: Rafael J. Wysocki <rjw@xxxxxxx>
> > > > > Date:   Mon Apr 5 01:43:51 2010 +0200
> > > > > 
> > > > >     ACPI / PM: Move ACPI video resume to a PM notifier
> > > > > 
> > > > > And reverting this commit on 2.6.38 still made the problem go away.
> > > > > Looking at the commit above I don't saw any problem, and perhaps we have
> > > > > some bad bios here which by moving the resume of acpi video later
> > > > > triggers this bug. Also strange that on second suspend/resume everything
> > > > > is normal... (the regression here is just the video is blank on first
> > > > > resume).
> > > > > 
> > > > > I asked the reporter to try to increase brightness logged in remotely
> > > > > when the video is blank after first resume, but this didn't have any
> > > > > effect.
> > > > > 
> > > > > This was reported in https://bugs.launchpad.net/bugs/719620 (if reading
> > > > > I recommend to skip to comment #58 and later), I can't think of any
> > > > > solution besides trying to move acpi video resume perhaps back and
> > > > > depend on video device being resume first. I asked for more debugging
> > > > > information but got nothing unfortunately which could diagnose better
> > > > > this...
> > > > 
> > > > What graphics driver is used?
> > > 
> > > i915
> > 
> > In the KMS mode I guess?
> 
> Yes, in KMS mode.

OK, I have no idea how to fix this.

Matthew, can you please have a look here?

Rafael
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