Created attachment 142019 [details] 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
Created attachment 142020 [details] Screen slightly affected
Created attachment 142021 [details] Screen affected up to one third of screen
FWIW, if drm_hwcomposer uses the vertical blank interrupt for flip completion, that's a drm_hwcomposer bug. Page flips generate their own events signalling completion.
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