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      <base href="https://bugs.freedesktop.org/" />
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    <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 --- - [HSW 3.8.2 regression] After running testdisplay with only eDP, screen turn to black and can't light up again"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=62275">62275</a>
          </td>
        </tr>

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

        <tr>
          <th>Summary</th>
          <td>[HSW 3.8.2 regression] After running testdisplay with only eDP, screen turn to black and can't light up again
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>critical
          </td>
        </tr>

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

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>yangweix.shui@intel.com
          </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>DRM/Intel
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>DRI
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Description:
----------------------------------
It's a new regression of HSW on 3.8.2 kernel:
[19b00d2dc9bedf0856e366cb7b9c7733ded659e4] Linux 3.8.2

I find 3.8 kernel is good:
[19f949f52599ba7c3f67a5897ac6be14bfcb1200] Linux 3.8

Our machine is lent to other team for a period, I will attach the attachment
later.

Reproduce step:
----------------------------------
1. reboot with bad commit kernel
2. ./testdisplay
3. After display the mode, then screen turn to black and can't light up again

Bisect result:
----------------------------------
719429a54d9c8fd32d457c7d564d1272d9003282 is the first bad commit
commit 719429a54d9c8fd32d457c7d564d1272d9003282
Author: Daniel Vetter <<a href="mailto:daniel.vetter@ffwll.ch">daniel.vetter@ffwll.ch</a>>
Date:   Wed Feb 6 11:24:41 2013 +0100

    drm/i915: write backlight harder

    commit cf0a6584aa6d382f802f2c3cacac23ccbccde0cd upstream.

    770c12312ad617172b1a65b911d3e6564fc5aca8 is the first bad commit
    commit 770c12312ad617172b1a65b911d3e6564fc5aca8
    Author: Takashi Iwai <<a href="mailto:tiwai@suse.de">tiwai@suse.de</a>>
    Date:   Sat Aug 11 08:56:42 2012 +0200

        drm/i915: Fix blank panel at reopening lid</pre>
        </div>
      </p>
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