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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO --- - [i945GM regression] in 3.7.0 kernel on macbook1,1 (kernel crash)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=58396#c8">Comment # 8</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO --- - [i945GM regression] in 3.7.0 kernel on macbook1,1 (kernel crash)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=58396">bug 58396</a>
from <span class="vcard"><a class="email" href="mailto:peter.ujfalusi@gmail.com" title="Peter Ujfalusi <peter.ujfalusi@gmail.com>"> <span class="fn">Peter Ujfalusi</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=58396#c7">comment #7</a>)
<span class="quote">> Created <span class=""><a href="attachment.cgi?id=71656" name="attach_71656" title="dump encoder responsible for modeset">attachment 71656</a> <a href="attachment.cgi?id=71656&action=edit" title="dump encoder responsible for modeset">[details]</a></span> <a href='page.cgi?id=splinter.html&bug=58396&attachment=71656'>[review]</a> [review]
> dump encoder responsible for modeset
>
> Also please apply this little debug patch on top of a broken kernel and
> readd a new dmesg with drm debug enabled.
>
> Analysis thus far is that we do a completely bogus modeset on the 2nd crtc,
> but while actually disabling the 1st crtc. Hence caller supplies no mode,
> and we fall over with a NULL deref trying to prepare the modeset on the 2nd
> crtc. Above patch might shed clue on why we try to do that bogus modeset.</span >
Will do. Meanwhile I looked at the offending patch:
fa55583 drm/i915: fixup the plane->pipe fixup code
The new check does not match the removed one so the code in
intel_sanitize_crtc()
will going to take different path.
Snippet from the patch:
+
+ if ((val & DISPLAY_PLANE_ENABLE) &&
+ (!!(val & DISPPLANE_SEL_PIPE_MASK) == crtc->pipe))
+ return false;
+
...
-
- if ((val & DISPLAY_PLANE_ENABLE) == 0 &&
- (!!(val & DISPPLANE_SEL_PIPE_MASK) == crtc->pipe))
- goto ok;
-
I'm mostly confident that this is the root cause of the issue I'm seeing.
I'l attach a patch to the bug to fix it. I have not tested it, but going to do
that as soon as I got home.</pre>
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