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

        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - Dual onboard LCD (eDP1 and DP1) cannot turn on DP1 (no backlight), no backlight control but can see screen in reflected light"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=73156">73156</a>
          </td>
        </tr>

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

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

        <tr>
          <th>Summary</th>
          <td>Dual onboard LCD (eDP1 and DP1) cannot turn on DP1 (no backlight), no backlight control but can see screen in reflected light
          </td>
        </tr>

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

        <tr>
          <th>Hardware</th>
          <td>x86-64 (AMD64)
          </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>Created <span class=""><a href="attachment.cgi?id=91333" name="attach_91333" title="intel_reg_dumper, lspci, xrandr, etc">attachment 91333</a> <a href="attachment.cgi?id=91333&action=edit" title="intel_reg_dumper, lspci, xrandr, etc">[details]</a></span>
intel_reg_dumper, lspci, xrandr, etc

Laptop: Asus Taichi 31 (same problem on Asus Taichi 21)

It has two embedded LCD.
Internal on eDP1 and external on DP1.

Start laptop with lid opened:
- external (DP1) screen backlight off
- internal (eDP1) screen backlight on
- change brighness work on internal
- cannot turn on external
- go to sleep and back, after internal screen backlight work
- lid_open* logs in attach (intel_reg_dumper, lspci, xrandr, etc)

Start laptop with lid closed:
- external (DP1) screen backlight on
- internal (eDP1) screen backlight off
- change brighness work on internal!
- if lid open internal screen turn on, and change backlight work, but no image
on it
- lid_closed_boot* logs in attach

- go to sleep and back, after external screen without backlight
- internal the same: there is backlight but no image
- lid_closed_sleep* logs in attach

test on 3.13-rc6 2013-12-30 same

I can get more info/compile/debug/test with your advice.</pre>
        </div>
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