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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 - i915 vlv blank screen after drm initialisation (4.4.0 mainline & drm-intel-nightly)"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=93845">93845</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>i915 vlv blank screen after drm initialisation (4.4.0 mainline & drm-intel-nightly)
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>DRI
          </td>
        </tr>

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

        <tr>
          <th>Hardware</th>
          <td>x86-64 (AMD64)
          </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>DRM/Intel
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>greg@gothack.ninja
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=121255" name="attach_121255" title="dmesg">attachment 121255</a> <a href="attachment.cgi?id=121255&action=edit" title="dmesg">[details]</a></span>
dmesg

Attempting to get linux booting on a Vulcan Excursion XB, having issues with
i915 (nomodeset / efi graphics work okay).

Black screen - with backlight - after i915 is initialised, I've made some dumps
of dmesg, etc. everything looks okay besides a backtrace for a suspicious
warning:
[   11.122021] WARNING: CPU: 2 PID: 161 at drivers/gpu/drm/drm_irq.c:1271
drm_wait_one_vblank+0x1c4/0x1d0 [drm]()
[   11.122022] vblank wait timed out on crtc 0

Also note the backlight control also seems like it could be busted:
[    8.151269] [drm:pwm_setup_backlight [i915]] *ERROR* Failed to own the pwm
chip
[    8.151287] [drm:intel_panel_setup_backlight] failed to setup backlight for
connector DSI-1

I also had issues dumping the vbios, no amount of prodding gave me a successful
dump (echo 1 > rom; cat rom; echo 0 > rom, nor intel_bios_dumper [the latter of
which gives me "Couldn't read graphics card ROM: Input/output error" - I'll try
looking at an strace]). Any suggestions there would be appreciated.</pre>
        </div>
      </p>
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