[Bug 99766] New: [PATCH] DisplayPort Monitor Doesn't Come Back From Sleep

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=99766

            Bug ID: 99766
           Summary: [PATCH] DisplayPort Monitor Doesn't Come Back From
                    Sleep
           Product: DRI
           Version: XOrg git
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: palmer at dabbelt.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

Created attachment 129490
  --> https://bugs.freedesktop.org/attachment.cgi?id=129490&action=edit
drm/i915: Fix DisplayPort Hotplug

I recently updated to Linux 4.9 (via Gentoo's kernel, but I used Linus' git
tree when bisecting and fixing the bug, and it appears on v4.9 there as well)
and discovered that my DisplayPort monitor doesn't come back from sleep any
more.  I bisected the problem back to 

commit 7d23e3c37bb3fc6952dc84007ee60cb533fd2d5c
Author: Shubhangi Shrivastava <shubhangi.shrivastava at intel.com>
Date:   Wed Mar 30 18:05:23 2016 +0530

    drm/i915: Cleaning up intel_dp_hpd_pulse

    Current DP detection has DPCD operations split across
    intel_dp_hpd_pulse and intel_dp_detect which contains
    duplicates as well. Also intel_dp_detect is called
    during modes enumeration as well which will result
    in multiple dpcd operations. So this patch tries
    to solve both these by bringing all DPCD operations
    in one single function and make intel_dp_detect
    use existing values instead of repeating same steps.

This looks a whole lot like
<https://bugs.freedesktop.org/show_bug.cgi?id=89453>, and the fix looks really
similar too, but the bug is still there on 4.9 so it's not a duplicate.

I've attached a patch that fixes the problem for me when applied on top of 4.9.
 It applies cleanly on Linus' master, but I haven't tried running it.

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