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      <base href="https://bugs.freedesktop.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - MST backport to 3.16 crashes"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=89187">89187</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>MST backport to 3.16 crashes
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>xorg
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>git
          </td>
        </tr>

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

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

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

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

        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

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

        <tr>
          <th>Assignee</th>
          <td>chris@chris-wilson.co.uk
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>dariusz.gadomski@canonical.com
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=113571" name="attach_113571" title="Kernel config used">attachment 113571</a> <a href="attachment.cgi?id=113571&action=edit" title="Kernel config used">[details]</a></span>
Kernel config used

I have built kernel from sources [1] containing David Airlie's MST i915
backport for the 3.16 kernel. I have used Ubuntu config (attached).

After connecting daisy-chained monitors (Dell U2414H) I get the following stack
trace:

[   38.186428] CPU: 1 PID: 2395 Comm: Xorg Tainted: G        W  OE 3.16.0+ #1
[   38.186429] Hardware name: Dell Inc. XPS 15 9530/XPS 15 9530, BIOS A07
10/15/2014
[   38.186430]  0000000000000009 ffff8803f83378c8 ffffffff82759c3f
ffff8803f8337910
[   38.186433]  ffff8803f8337900 ffffffff8206d97d ffff880412735058
ffff8804127356f8
[   38.186435]  ffff880414866800 ffff880412735000 ffff880414866b40
ffff8803f8337960
[   38.186437] Call Trace:
[   38.186440]  [<ffffffff82759c3f>] dump_stack+0x45/0x56
[   38.186443]  [<ffffffff8206d97d>] warn_slowpath_common+0x7d/0xa0
[   38.186445]  [<ffffffff8206d9ec>] warn_slowpath_fmt+0x4c/0x50
[   38.186456]  [<ffffffffc064cd63>] check_crtc_state+0x703/0xd70 [i915]
[   38.186469]  [<ffffffffc065b24f>] intel_modeset_check_state+0x28f/0x7a0
[i915]
[   38.186479]  [<ffffffffc065b7f5>] intel_set_mode+0x25/0x30 [i915]
[   38.186490]  [<ffffffffc065c73c>] intel_crtc_set_config+0x92c/0xe00 [i915]
[   38.186499]  [<ffffffffc042e421>] drm_mode_set_config_internal+0x61/0xe0
[drm]
[   38.186508]  [<ffffffffc0431f99>] drm_mode_setcrtc+0xd9/0x590 [drm]
[   38.186515]  [<ffffffffc04229cc>] drm_ioctl+0x1ec/0x660 [drm]
[   38.186519]  [<ffffffff821e4e10>] do_vfs_ioctl+0x2e0/0x4c0
[   38.186521]  [<ffffffff820a4c84>] ? vtime_account_user+0x54/0x60
[   38.186524]  [<ffffffff821e5071>] SyS_ioctl+0x81/0xa0
[   38.186526]  [<ffffffff827627bf>] tracesys+0xe1/0xe6
[   38.186528] ---[ end trace 8b3dd31c3c6e8ccc ]---


Attaching full dmesg and another dmesg with drm.debug=1 passed on the kernel
command line.

I am using intel drivers built from git available here [2] (version
147e190d1e18d3ac6dc23aa4e493eec28aa75d1d).

[1] <a href="http://cgit.freedesktop.org/~airlied/linux/log/?h=drm-i915-mst-v3.16">http://cgit.freedesktop.org/~airlied/linux/log/?h=drm-i915-mst-v3.16</a>
[2] <a href="https://launchpad.net/~xorg-edgers/+archive/ubuntu/ppa">https://launchpad.net/~xorg-edgers/+archive/ubuntu/ppa</a></pre>
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