Minimal code to reproduce flip done time out when running with the KMS driver on RPI.

To build & run first time...

git clone https://github.com/pjx3/kms_fdto.git
cd kms_fdto
cmake .
make
kms_fdto/kms_fdto

Should produce a triangle on screen (you may need to edit the source to set the right render width & height).

To reproduce the flip done timeout

• Edit kms_fdto/kms_fdto.cpp line 1228 to enable the call to snd_pcm_writei
• Rebuild & run
• This time the screen will be black, the time out will show on the kernel log & my code will eventually assert

After this the system is generally unstable, so I usually reboot.

Enable DRM debug output to see where the first timeout occurs (during drm_mode_setcrtc())

echo 0x3ff | sudo tee /sys/module/drm/parameters/debug

Two threads:-

• main thread is rendering the triangle using Vulkan (most of this is boilerplate)
• audio thread polls for ALSA buffer descriptors requesting next audio buffer period & then submits it with snd_pcm_writei

• vulkan
• asound2
• pthreads