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    <head>
      <base href="https://bugs.freedesktop.org/" />
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - HDMI gives no more signal"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=84203">84203</a>
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>nouveau@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>HDMI gives no more signal
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>xorg-team@lists.x.org
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux (All)
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>jean-louis@dupond.be
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Driver/nouveau
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>xorg
          </td>
        </tr></table>
      <p>
        <div>
        <pre>This week I tried HDMI again on my system, and noticed it was completely
broken.
Got just no signal on my screen.

I knew it was working some months (and upgrades) ago.
After testing I found out the issue was introduced between kernel v3.14 and
v3.15.

Situation:
Insert HDMI cable into my laptop, and no signal on the external display.

The dmesg fills with errors also:
[  186.210622] nouveau E[   PDISP][0000:01:00.0] INVALID_STATE [UNK08] chid 0
mthd 0x0080 data 0x00000000
[  186.210627] nouveau E[   PDISP][0000:01:00.0] Core:
[  186.210634] nouveau E[   PDISP][0000:01:00.0]     0x0084: 0x5dc34da1 ->
0x80000000
[  186.210640] nouveau E[   PDISP][0000:01:00.0]     0x0088: 0x00000000         

etc.

After some git bisect playtime, I found out the following commit caused the
issue:
<a href="https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/nouveau?id=05c63c2ff23a80b654d6c088ac3ba21628db0173">https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/nouveau?id=05c63c2ff23a80b654d6c088ac3ba21628db0173</a>

So I went back to stable 3.16 (Ubuntu Utopic version), and did a git revert for
that commit.
And yep, HDMI output was working again, and no more nouveau errors in dmesg.


My device:
[   30.823267] nouveau  [  DEVICE][0000:01:00.0] BOOT0  : 0x0c1a00a1
[   30.823269] nouveau  [  DEVICE][0000:01:00.0] Chipset: GF108 (NVC1)
[   30.823270] nouveau  [  DEVICE][0000:01:00.0] Family : NVC0

Laptop dell xps 15 l502x</pre>
        </div>
      </p>
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