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            <b><a class="bz_bug_link 
          bz_status_NEEDINFO "
   title="NEEDINFO - [pnv] panel assertion failure, pipe B regs locked at boot"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=79824#c9">Comment # 9</a>
              on <a class="bz_bug_link 
          bz_status_NEEDINFO "
   title="NEEDINFO - [pnv] panel assertion failure, pipe B regs locked at boot"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=79824">bug 79824</a>
              from <span class="vcard"><a class="email" href="mailto:jbarnes@virtuousgeek.org" title="Jesse Barnes <jbarnes@virtuousgeek.org>"> <span class="fn">Jesse Barnes</span></a>
</span></b>
        <pre>A hack to try:

diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index c424c36..a19544b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1607,7 +1607,9 @@ static void i9xx_enable_pll(struct intel_crtc *crtc)
     BUG_ON(INTEL_INFO(dev)->gen >= 5);

     /* PLL is protected by panel, make sure we can write it */
-    if (IS_MOBILE(dev) && !IS_I830(dev))
+    if (IS_MOBILE(dev) && !IS_I830(dev) &&
+        (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS) ||
+         intel_pipe_has_type(crtc, INTEL_OUTPUT_EDP)))
         assert_panel_unlocked(dev_priv, crtc->pipe);

     /* Enable DVO 2x clock on both PLLs if necessary */</pre>
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