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<body><span class="vcard"><a class="email" href="mailto:diwic@ubuntu.com" title="David Henningsson <diwic@ubuntu.com>"> <span class="fn">David Henningsson</span></a>
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<a class="bz_bug_link
bz_status_NEW "
title="NEW - [dc][kabini] Cannot find any crtc or sizes"
href="https://bugs.freedesktop.org/show_bug.cgi?id=105880">bug 105880</a>
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<th>What</th>
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<td>diwic@ubuntu.com
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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - [dc][kabini] Cannot find any crtc or sizes"
href="https://bugs.freedesktop.org/show_bug.cgi?id=105880#c8">Comment # 8</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - [dc][kabini] Cannot find any crtc or sizes"
href="https://bugs.freedesktop.org/show_bug.cgi?id=105880">bug 105880</a>
from <span class="vcard"><a class="email" href="mailto:diwic@ubuntu.com" title="David Henningsson <diwic@ubuntu.com>"> <span class="fn">David Henningsson</span></a>
</span></b>
<pre>Hi,
I'm getting the same or similar error:
* Black screen, no plymouth
* "Cannot find any crtc or sizes" error in dmesg
* amdgpu.dc=0 works around the issue
...and I might have a lead on it. The regression is between 4.15rc2 and 4.15rc3
(found by downloading kernels from
<a href="http://kernel.ubuntu.com/~kernel-ppa/mainline/">http://kernel.ubuntu.com/~kernel-ppa/mainline/</a>).
The only one commit I could see being relevant between 4.15rc2 and 4.15rc3 is
this one:
commit a703c55004e1c5076d57e43771b3e11117796ea0
Author: Daniel Vetter <<a href="mailto:daniel.vetter@ffwll.ch">daniel.vetter@ffwll.ch</a>>
Date: Mon Dec 4 21:48:18 2017 +0100
drm: safely free connectors from connector_iter
...it seems relevant because the error I get is "Cannot find any crtc or
sizes", and the code emitting this error message (in
drivers/gpu/drm/drm_fb_helper.c) deals with connectors.
So could this commit cause connectors to be freed where the previous code did
not? It seems like this could be the case, but only if (obj->free_cb == NULL) -
drm_connector_put checks for a obj->free_cb being null whereas
drm_connector_put_safe decrements a refcount regardless of whether a free_cb is
present or not.
Does all this make sense, or am I out on deep water here?</pre>
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