[Intel-gfx] black screen if sna & TearFree

[Grant]

>>> > I'm using a Dell XPS 13 laptop on Gentoo and if I use:
>>> >
>>> > Option "AccelMethod" "sna"
>>> > Option "TearFree" "true"
>>> >
>>> > my video tearing problem disappears, but if I close my laptop lid for
>>> > a few minutes, it comes back up with a black screen, although I can
>>> > get my session back if I switch to VT1 and then back to VT7.  I can't
>>> > find anything in the logs.  I've tried xf86-video-intel-2.20.3 as well
>>> > as the latest from git.  The problem doesn't occur without the above
>>> > two directives.
>>> >
>>> > Does anyone know how to diagnose or fix this?
>>> >
>>> > - Grant
>>>
>>> I can prevent this if I issue 'xset -dpms' before closing the laptop
>>> lid, but xlockmore automatically re-enables dpms unfortunately.  BTW,
>>> this does not prevent the problem:
>>
>> The implication would seem to be that an action during dpms is going
>> wrong. Does a simple 'xset dpms force off; sleep 1; xset dpms force on'
>> trigger the error? If so can you please attach your Xorg.0.log and if
>> you could compile with --enable-debug=full and send me the log
>> reproducing the error that would be very helpful.
>>
>> Thanks,
>> -Chris
>
> 'xset dpms force off; sleep 1; xset dpms force on' does indeed trigger
> the error.  I've attached my Xorg.0.log.old which includes the
> segfault backtrace.  I'm like a newborn baby when it comes to
> compiling and Gentoo doesn't have a debug USE flag for
> xf86-video-intel or xorg-server so I can't help there.  Is there a
> different package I should check for a debug USE flag?
>
> - Grant
>
> P.S. Sorry for the multiple sends.

It looks like I also need to do 'xset s 0' because X also crashes if
the screensaver comes on for more than a few seconds.

Screen Saver:
  prefer blanking:  yes    allow exposures:  yes
  timeout:  0    cycle:  600

Maybe it has something to do with turning off the backlight?

- Grant