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.
Good luck!
>
> Cc: Marissa Wall <marissaw@xxxxxxxxxx>
> Cc: Sean Paul <seanpaul@xxxxxxxxxx>
> Cc: Dmitry Shmidt <dimitrysh@xxxxxxxxxx>
> Cc: Robert Foss <robert.foss@xxxxxxxxxxxxx>
> Cc: Matt Szczesiak <matt.szczesiak@xxxxxxx>
> Cc: Liviu Dudau <Liviu.Dudau@xxxxxxx>
> Cc: David Hanna <david.hanna11@xxxxxxxxx>
> Cc: Rob Herring <rob.herring@xxxxxxxxxx>
> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
> ---
> v2:
> * Simplified, focusing on the key glFinsh() call
> ---
> drmdisplaycompositor.cpp | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drmdisplaycompositor.cpp b/drmdisplaycompositor.cpp
> index 3a20b31..eb0b77a 100644
> --- a/drmdisplaycompositor.cpp
> +++ b/drmdisplaycompositor.cpp
> @@ -439,6 +439,10 @@ int DrmDisplayCompositor::PrepareFrame(DrmDisplayComposition *display_comp) {
>
> fb.set_release_fence_fd(ret);
> ret = 0;
> + } else {
> + /*If we're not doing anything, block to avoid tearing */
> + glFinish();
> + return 0;
> }
> }
>
> --
> 2.7.4
>
--
Sean Paul, Software Engineer, Google / Chromium OS
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