Description of problem: login screen and desktop wayland session are jerking on Intel® Sandybridge Demonstration: https://drive.google.com/file/d/0B0nwzlfiB4aQMlhfQ0d4NXBsNE0/view?usp=sharing (Please use Google Chrome for HD quality)
For monitor connection used HDMI.
Add drm.debug=0xe to your kernel command line then repeat the steps you followed on that video and attach the output of dmesg to this bug report.
Created attachment 115880 [details] dmesg
The dmesg got truncated. Can you also add log_buf_len=4M to the kernel command line and try again?
Created attachment 115882 [details] dmesg
It seems that when wayland starts the CRTC is active but the primary plane doesn't have an FB. A call to drmModeCursor() is done before any mode set, and that causes the watermarks to be updated, but the update considers the CRTC is inactive because of the lack of a primary fb. The drmModeSetCrtc() call that follows is short circuited to a flip, so that also doesn't update the watermarks, causing the system to run with watermarks set for a disabled CRTC.
Could you test the following patch? http://lists.freedesktop.org/archives/intel-gfx/2015-May/067008.html
that patch works on a machine I was testing with.
(In reply to Ander Conselvan de Oliveira from comment #7) > Could you test the following patch? > > http://lists.freedesktop.org/archives/intel-gfx/2015-May/067008.html Today I received kernel-4.0.4-301 which included this patch and the problem disappeared. Thanks!
(In reply to mikhail.v.gavrilov from comment #9) > (In reply to Ander Conselvan de Oliveira from comment #7) > > Could you test the following patch? > > > > http://lists.freedesktop.org/archives/intel-gfx/2015-May/067008.html > > Today I received kernel-4.0.4-301 which included this patch and the problem > disappeared. > Thanks! Okay, so we've fixed this upstream. That patch was a backport for stable. I can't find it committed to upstream stable kernels, however. Perhaps it's just in some distro kernels? In any case, the bug has been fixed upstream, closing. Please reopen if the problem persists with latest kernels.
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