[REGRESSION, i915]: Periodic stalls with 2.6.36-rc2

[Peter Stuge]

Hi again,

Chris Wilson wrote:
> > In general, Xv performance with KMS leaves me with a feeling that
> > something is not quite right in terms of playback, both with mplayer
> > and vlc. But while movies are nice, this stalling issue is more
> > important.
> 
> That should now be fixed in -intel,

Sounds good! I'd love to test. Which branch/commit is that? I just
pulled and am using 68a5ad4.

mplayer -vo gl or gl2 works but uses sw rendering and is very slow.

Incidentally, apropos the backlight commit in xf86-video-intel, it
seems like the driver always sets the backlight to 0. Whenver I start
X, backlight goes to minimum. I can crank it up with Fn+Home, but if
I restart X then it goes back down again.

/proc/acpi/ibm/brightness is always accurate, showing 0 after X
starts.


> However, we have we replaced it with a worse bug...

Oh well..


> > I get the stall precisely every 10 seconds.
> 
> This is caused by the hotplug polling code taking around 600ms to
> determine that the VGA is not connected.

Ouch. Could it rely on DDC? Maybe a quick DDC query could be done
first, and if that seems to indicate that something is connected
only then do the heavy work reading the border color?


> https://bugs.freedesktop.org/show_bug.cgi?id=29536

Lovely! The patch works well for me, booting with
drm_kms_helper.poll=0 on the kernel command line, and I'm back in X
now. I need to sort out some keyboard issues, but they are unrelated.

The commit message mentions runtime switching of the polling - how is
that done? As I understand it I might have to do that in order to run
xrandr e.g. to set up a projector, or possibly after - or no?


> > I've just upgraded my userspace and have xorg-server-1.8.2. No Xv
> > image with either xf86-video-intel driver. I haven't tried this
> > server with the 07-21 kernel to find out if Xv works there. The
> > stalling is more important.
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=29574 (I think, Daniel
> reported something closer to your issue on IRC, but I don't have an
> actual bug for that.)

Disabling polling made no difference for Xv. I will try to merge your
overlay branch.


> > drm-intel.git (Should I look elsewhere?)
> 
> No, sounds like you've hit almost all of the recent 855 regressions.

.36-rc2 is the first kernel in what seems like a long time that feels
like a solid improvement, even if there are still some issues.
Well done!


> But you have a cursor, that is more than most people!

Funny you should say that! :) Actually I *don't* have a cursor in X
on cold boot, but it shows up after suspend+resume.

The cursor I mentioned is the VT blinking one.


> very pessimistic guess for the memory fetch

Aha. Thanks for the explanation!


//Peter