On Wed, Jan 24, 2018 at 7:26 AM, Sean Paul <seanp...@chromium.org> wrote: > On Tue, Jan 23, 2018 at 03:16:39PM -0800, John Stultz wrote: >> When using drm_hwcomposer with the hikey board, the resulting >> display shows lots of tearing. >> >> This seems to be due to EGLcomposition not initializing >> properly, potentially due to I'm guessing limitations of what >> the utgard mali driver can do. I've noted that with the >> HiKey960 board, this patch is *not* necessary. >> >> Hacking around a bit, I found that since the glworker code >> isn't running properly, we never call glFinish(), which >> is required to fix the tearing. >> >> Ideas for a better way to implement this would be greatly >> appreciated! > > Sounds like you'll have to dig into the gl compositor to fix this. I think > chances are quite good there's a better way than below.
Yes, I did spent a little bit of time earlier trying to rewrite the gl shader to try to build for the utgard level hardware, but wasn't very successful. At a deeper level I guess I'm not sure the glcompositor is useful in this case, since we're doing single plane client side compositing (as short of the glFinish bit, not running it doesn't seem to keep things from working). But I'll look into that again. Again forgive as I really a bit in the dark on most graphics details, but the other more basic question I'm a bit unsure of is, does this patch even make any functional sense? If we're not using the glcompositor and are using the atomic commit in ApplyFrame(), why the need for glFinish to avoid tearing? Is it that the we commit the frame atomically to the display, but if we don't block w/ glFinish() the gpu is still drawing into it? It seems we'd want a buffer specific fence to wait on rather then waiting for all gl calls to complete (if I'm understanding how glFinish() works). Thanks again for your review feedback! thanks -john _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
