<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - screen corruption using SNA and TearFree on Intel GeminiLake" href="https://bugs.freedesktop.org/show_bug.cgi?id=105720#c12">Comment # 12</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - screen corruption using SNA and TearFree on Intel GeminiLake" href="https://bugs.freedesktop.org/show_bug.cgi?id=105720">bug 105720</a> from <a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> Chris Wilson</a> <pre>Created <a href="attachment.cgi?id=138363" name="attach_138363" title="Ratelimit per-CRTC updates without TearFree">attachment 138363</a> <a href="attachment.cgi?id=138363&action=edit" title="Ratelimit per-CRTC updates without TearFree">[details]</a> <a href='page.cgi?id=splinter.html&bug=105720&attachment=138363'>[review]</a> Ratelimit per-CRTC updates without TearFree So looking at the code, the easiest way to buffer output onto the CRTC is via Option "PerCRTCPixmap". We can replace Option "TearFree" (or force Option "NoTearFree") with the attached as a rough approximation to scheduling the screen update via vblank (v.rough, it definitely does not prevent tearing!), and it definitely feels heavier than TearFree (presumably due to the synchronisation on the extra forced copy). Testing on bdw/skl showed no sign of the "blank screen", but there's a fishy !rr_active() in the middle of initialising the crtc pixmap that needs double checking (I suspect that actually should be if !(flags & TEAR_FREE)) and may be the cause of the delayed init. Option "PerCRTCPixmap" + Option "TearFree" should work together, that's akin to triple buffering, as the CRTC flips are double buffered with the ScreenPixmap being the third copy as rendered to by the clients. Without the feedback loop, it should be impervious to the accumulation of dirt, but it may still exhibit the wrong buffer syndrome (if the event accounting is completely skewiff), e.g. glxgears going backwards. The drawback is that at best it should instill an extra frame of input-output latency, and at worst that latency may jitter.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>