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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 - [IVB] video output failed resume from RAM, [drm:intel_dp_start_link_train] *ERROR* failed to enable link training"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=91796">91796</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[IVB] video output failed resume from RAM,  [drm:intel_dp_start_link_train] *ERROR* failed to enable link training
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>DRI git
          </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>chris.bainbridge@gmail.com
          </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=117971" name="attach_117971" title="dmesg">attachment 117971</a> <a href="attachment.cgi?id=117971&action=edit" title="dmesg">[details]</a></span>
dmesg

Observed on Linux 4.2.0-rc7
Hardware IvyBridge Macbook with triple monitors

One monitor failed to come back after suspend to ram
Using xrandr --off then --auto successfully turned the monitor back on

dmesg with drm.debug=0xe attached, relevant bit is:

[207696.676767] [drm:intel_get_shared_dpll] using PCH DPLL B for pipe B
[207696.676770] [drm:intel_prepare_shared_dpll] setting up PCH DPLL B
[207696.677329] [drm:cpt_set_fdi_bc_bifurcation] enabling fdi C rx
[207696.677489] [drm:ivb_manual_fdi_link_train] FDI_RX_IIR before link train
0x0
[207696.677497] [drm:ivb_manual_fdi_link_train] FDI_RX_IIR 0x100
[207696.677498] [drm:ivb_manual_fdi_link_train] FDI train 1 done, level 0.
[207696.677505] [drm:ivb_manual_fdi_link_train] FDI_RX_IIR 0x200
[207696.677507] [drm:ivb_manual_fdi_link_train] FDI train 2 done, level 0.
[207696.677507] [drm:ivb_manual_fdi_link_train] FDI train done.
[207696.677510] [drm:intel_enable_shared_dpll] enable PCH DPLL B (active 0, on?
0) for crtc 25
[207696.677511] [drm:intel_enable_shared_dpll] enabling PCH DPLL B
[207696.681419] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7145003f
[207696.685001] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7145003f
[207696.689080] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7145003f
[207696.690500] [drm:intel_dp_sink_dpms] failed to enable sink power state
[207696.693080] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7145003f
[207696.695653] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7145003f
[207696.695658] [drm:intel_dp_set_signal_levels] Using signal levels 04000000
[207696.695659] [drm:intel_dp_set_signal_levels] Using vswing level 2
[207696.695660] [drm:intel_dp_set_signal_levels] Using pre-emphasis level 0
[207696.698271] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7145003f
[207696.698279] [drm:intel_dp_start_link_train] *ERROR* failed to enable link
training
[207696.700892] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7145003f
[207696.700898] [drm:intel_dp_complete_link_train] *ERROR* failed to start
channel equalization
[207696.703424] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7145003f</pre>
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