Pinebook pro: Occasional KMS update failures (black flickering) on cursor image updates
Playing around with the rather low-end Pinebook Pro (Rockchip RK3399) I occasionally get KMS update errors, visible by a black flashing of the screen. These appear to happen when the cursor image was going to be updated. In the logs there are usually a bunch of these lines, especially the last two:
Failed to scan out client buffer: drmModeAddFB does not support format 'AR24' (0x34325241)
Failed to post KMS update: drmModeAddFB does not support format 'AR24' (0x34325241)
Page flip discarded: drmModeAddFB does not support format 'AR24' (0x34325241)
Most commonly the issue happens with rather "heavy" (for this device) OpenGL clients like Firefox running a WebGL page or the gtk4-widget-factory
, especially when fullscreen with direct scanout. And interestingly !1880 (merged) seems to help prevent those flickers most of the time.
Initial theory: implicit sync delays a KMS update with cursor update. By the time the update happens the cursor image is already gone somehow or the Rockship atomic KMS kernel driver is buggy.