Bug 93945

Summary: [ILK] [v4.5-rc1] FIFO underrun and flickering screen on cursor hide
Product: DRI Reporter: Peter Wu <peter>
Component: DRM/IntelAssignee: Matt Roper <matthew.d.roper>
Status: CLOSED FIXED QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium CC: intel-gfx-bugs, matthew.d.roper, peter
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:

Description Peter Wu 2016-01-31 10:38:30 UTC 
Since upgrading the kernel from v4.3 to v4.5-rc1-28-g03c21cb on a laptop
running Arch Linux (i5-560M), I experience a flickering screen when the cursor is hidden. This happens on both the internal LVDS panel and an external HDMI monitor.

Example dmesg lines:

[  192.695484] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun
[  192.696897] [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder A FIFO underrun

Steps to reproduce:

 1. Open Konsole (from KDE).
 2. Press Ctrl (cursor is hidden).
 3. Observe flickering screen (first occurrence, e.g. after suspend also results in dmesg entries).
 4. Move the pointer to make it visible again, possible repeating step 2 if 3 did not happen.

Alternative steps to reproduce:

 1. Have two monitors connected (internal LVDS and external HDMI).
 2. Move the mouse between them (back and forth).
 3. Observe a flickering screen on the monitor where the cursor left.
Comment 1 Matt Roper 2016-02-04 00:25:10 UTC 
I believe this should be fixed by http://patchwork.freedesktop.org/patch/72424/ which just went into drm-intel-nightly (and should be pulled over to the -fixes tree for 4.5 soon).
Comment 2 Peter Wu 2016-02-04 13:48:34 UTC 
Applied the patch on top of v4.5-rc2-192-gb37a05c (undoing http://cgit.freedesktop.org/drm-intel/commit/drivers/gpu/drm/i915/intel_pm.c?h=drm-intel-next-queued&id=ac484963f979b6ab490183f0e09a3a17175f5758), can confirm that the flickering is fixed.
Comment 3 Matt Roper 2016-02-09 22:26:06 UTC 
Patch is now merged to our -fixes tree and should show up in the next 4.5 RC.
Comment 4 Jari Tahvanainen 2016-10-10 13:24:52 UTC 
Closing resolved+fixed based on verification done by Reporter. Patch merged on drm-intel-nightly git tree on Feb 14, 2016 (commit 631c0e8).

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