i915: 2.6.36-rc2 wrong resolution on gdm start

[Pekka Enberg]

On Tue, Aug 24, 2010 at 4:00 AM, Ivan Bulatovic <combuster at gmx.com> wrote:
> While in init3, resolution is native, KMS works fine, no problems at
> all. As soon as gdm starts it seems that TV1 output is recognized as
> connected even if it isn't so resolution on VGA output is degraded from
> native 1280x1024 to 1024x768 on startup.
>
> I've disabled LVDS output with video=LVDS-1:d because the cable looses
> connection in certain lid positions.
>
> 2.6.36-rc1 didn't have this issue, 2.6.36-rc2 did so I've bisected and
> it came down to this commit:
>
> 9d0498a2bf7455159b317f19531a3e5db2ecc9c4 is the first bad commit
> commit 9d0498a2bf7455159b317f19531a3e5db2ecc9c4
> Author: Jesse Barnes <jbarnes at virtuousgeek.org>
> Date:   Wed Aug 18 13:20:54 2010 -0700
>
>    drm/i915: wait for actual vblank, not just 20ms
>
> Waiting for a hard coded 20ms isn't always enough to make sure a vblank
> period has actually occurred, so add code to make sure we really have
> passed through a vblank period (or that the pipe is off when disabling).
>
> This prevents problems with mode setting and link training, and seems to
> fix a bug like https://bugs.freedesktop.org/show_bug.cgi?id=29278, but
> on an HP 8440p instead.  Hopefully also fixes
> https://bugs.freedesktop.org/show_bug.cgi?id=29141.
>
>    Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
>    Signed-off-by: Eric Anholt <eric at anholt.net>
>
> :040000 040000 9941813d0f0bc4e141a87696d34f1d1b9087711b
> 2e407ad1d03b60f0e5b020313a8a63bd176b4005 M drivers
>
> I'm sending you dmesg, xorg and xrandr logs as attachements. GM965 on
> DELL Vostro 1310 is in question. Thanks,

On Tue, Aug 24, 2010 at 4:00 AM, Ivan Bulatovic <combuster at gmx.com> wrote:
> While in init3, resolution is native, KMS works fine, no problems at
> all. As soon as gdm starts it seems that TV1 output is recognized as
> connected even if it isn't so resolution on VGA output is degraded from
> native 1280x1024 to 1024x768 on startup.
>
> I've disabled LVDS output with video=LVDS-1:d because the cable looses
> connection in certain lid positions.
>
> 2.6.36-rc1 didn't have this issue, 2.6.36-rc2 did so I've bisected and
> it came down to this commit:
>
> 9d0498a2bf7455159b317f19531a3e5db2ecc9c4 is the first bad commit
> commit 9d0498a2bf7455159b317f19531a3e5db2ecc9c4
> Author: Jesse Barnes <jbarnes at virtuousgeek.org>
> Date:   Wed Aug 18 13:20:54 2010 -0700
>
>    drm/i915: wait for actual vblank, not just 20ms
>
> Waiting for a hard coded 20ms isn't always enough to make sure a vblank
> period has actually occurred, so add code to make sure we really have
> passed through a vblank period (or that the pipe is off when disabling).
>
> This prevents problems with mode setting and link training, and seems to
> fix a bug like https://bugs.freedesktop.org/show_bug.cgi?id=29278, but
> on an HP 8440p instead.  Hopefully also fixes
> https://bugs.freedesktop.org/show_bug.cgi?id=29141.
>
>    Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
>    Signed-off-by: Eric Anholt <eric at anholt.net>
>
> :040000 040000 9941813d0f0bc4e141a87696d34f1d1b9087711b
> 2e407ad1d03b60f0e5b020313a8a63bd176b4005 M drivers
>
> I'm sending you dmesg, xorg and xrandr logs as attachements. GM965 on
> DELL Vostro 1310 is in question. Thanks,

FWIW, I saw this on my MacBook as well. I was debugging a boot time
oops at the time so I just changed screen resolution in Gnome to fix
it.