AMD DC: Mullins APU: Possible race condition between vblank interrupt and atomic pageflip
Submitted by maurossi
Assigned to Default DRI bug account
Created attachment 142019
Screen without issue
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
Attachment 142019, "Screen without issue":