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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 --- - When using vgaswitcheroo intel i915 goes to black."
   href="https://bugs.freedesktop.org/show_bug.cgi?id=61115">61115</a>
          </td>
        </tr>

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

        <tr>
          <th>Summary</th>
          <td>When using vgaswitcheroo intel i915 goes to black.
          </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>All
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>william@firstyear.id.au
          </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>On a dual gpu macbook pro 8,2 with gmux under efi, after getting the system to
a sane state with:

cat /sys/kernel/debug/vgaswitcheroo/switch 
0:IGD: :Off:0000:00:02.0
1:DIS:+:Pwr:0000:01:00.0
2:DIS-Audio:+:Pwr:0000:01:00.1

running:

cd /sys/kernel/debug/vgaswitcheroo
echo OFF > switch
echo MIGD > switch
echo IGD > switch

To swap to the intel i915 causes the display to go blank. Swapping back to the
radeon, the display operates correctly again. 

Here is the dmesg from attempting to swap to the i915 then swapping back to the
radeon

[  138.004527] i915: switched on
[  138.015018] i915 0000:00:02.0: setting latency timer to 64
[  138.071523] ALSA sound/pci/hda/hda_intel.c:2811 0000:01:00.1: Disabling via
VGA-switcheroo
[  138.084388] [drm] Forcing lvds to dual link mode on Apple MacBook Pro (Core
i5/i7 Series)
[  138.483215] fbcon: Remapping primary device, fb0, to tty 1-63
[  138.483223] radeon: switched off
[  139.774545] [drm] Enabling RC6 states: RC6 on, RC6p off, RC6pp off
[  141.838901] radeon: switched on
[  141.849447] radeon 0000:01:00.0: Refused to change power state, currently in
D3
[  141.863465] [drm] probing gen 2 caps for device 8086:101 = 2/0
[  141.863469] [drm] PCIE gen 2 link speeds already enabled
[  141.892894] [drm] PCIE GART of 512M enabled (table at 0x0000000000040000).
[  141.894199] radeon 0000:01:00.0: WB enabled
[  141.894207] radeon 0000:01:00.0: fence driver on ring 0 use gpu addr
0x0000000040000c00 and cpu addr 0xffff88044d27dc00
[  141.894212] radeon 0000:01:00.0: fence driver on ring 3 use gpu addr
0x0000000040000c0c and cpu addr 0xffff88044d27dc0c
[  141.911507] [drm] ring test on 0 succeeded in 1 usecs
[  141.911667] [drm] ring test on 3 succeeded in 1 usecs
[  141.913479] [drm] ib test on ring 0 succeeded in 0 usecs
[  141.915154] [drm] ib test on ring 3 succeeded in 1 usecs
[  142.736845] fbcon: Remapping primary device, fb1, to tty 1-63
[  142.736866] i915: switched off
[  142.796919] ALSA sound/pci/hda/hda_intel.c:2811 0000:01:00.1: Enabling via
VGA-switcheroo
[  142.808969] snd_hda_intel 0000:01:00.1: irq 51 for MSI/MSI-X


This has never worked in any kernel versions, but would be excellent to have
fixed.</pre>
        </div>
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