[Bug 108356] AMD DC: Mullins APU: Possible race condition between vblank interrupt and atomic pageflip

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=108356

            Bug ID: 108356
           Summary: AMD DC: Mullins APU: Possible race condition between
                    vblank interrupt and atomic pageflip
           Product: DRI
           Version: DRI git
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/AMDgpu
          Assignee: dri-devel at lists.freedesktop.org
          Reporter: issor.oruam at gmail.com

Created attachment 142019
  --> https://bugs.freedesktop.org/attachment.cgi?id=142019&action=edit
Screen without issue

Hi,

while doing tests with AMD DC on Mullins APU (Acer ES1-521)
a visual problem has been observed on HDMI output to LCD monitor

>From visual point of view there is a trapezoidal shape at the top of screen
appearing from time to time, but it lasts a fraction of second.

Stack: drm_hwcomposer + gbm_gralloc with AMD DC
Kernel: all kernels from 4.16 to 4.19rc7 are impacted

I would like to understand what irq/signals are involved in the screen scanout
and how to trace/profile the problem in Android.
NOTE: even disabling the HWC, by forcing GPU compositing the problem is still
happening.

The problem does not happen at all with Bonaire (HD7790) and Polaris (RX560)
Visual representation of the rapid glitches in the attach

Thanks for any help

Mauro
android-x86 team

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