[Bug 72924] GPU overheating after running a full screen GL app on Sandy Bridge

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=72924

--- Comment #10 from Chris Wilson <chris at chris-wilson.co.uk> ---
For the rc6 commits, see:

commit 351aa5666d02062b52329bcfe4bcf9d1f882fba9
Author: Stéphane Marchesin <marcheu at chromium.org>
Date:   Tue Aug 13 11:55:17 2013 -0700

    drm/i915: tune the RC6 threshold for stability

    It's basically the same deal as the RC6+ issues on ivy bridge
    except this time with RC6 on sandy bridge. Like last time the
    core of the issue is that the timings don't work 100% with our
    voltage regulator. So from time to time, the kernel will print
    a warning message about the GPU not getting out of RC6. In
    particular, I found this fairly easy to reproduce during
    suspend/resume.

    Changing the threshold to 125000 instead of 50000 seems to fix
    the issue. The previous patch used 150000 but as it turns out
    this doesn't work everywhere. After getting such a machine, I
    bisected the highest value which works, which is 125000, so here
    it is.

    I also measured the idle power usage before/after this patch and
    didn't see a difference on a sandy bridge laptop. On haswell and
    up, it makes a big difference, so we want to keep it at 50k
    there. It also seems like haswell doesn't have the RC6 issues
    that sandy bridge has so the 50k value is fine.

    Signed-off-by: Stéphane Marchesin <marcheu at chromium.org>
    Acked-by: Jesse Barnes <jbarnes at virtuousgeek.org>
    Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>


commit 29c78f609e661e663a239a37923adb1d61f6386c
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Sat Nov 16 16:04:26 2013 +0100

    Partially revert "drm/i915: tune the RC6 threshold for stability"

    This reverts commit 351aa5666d02062b52329bcfe4bcf9d1f882fba9.

    It breaks rc6 on at least one snb machine. Since we don't yet have a
    report for ivb let's keep it there for now.

    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71656
    Cc: Stéphane Marchesin <marcheu at chromium.org>
    Cc: erik at vontaene.de
    Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>


But if 3.13 is cooler, that suggests it was RPS (gpu frequency).

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