Messages in this thread | | | Date | Wed, 22 Jun 2022 20:41:57 +0300 | Subject | Re: [PATCH] drm/msm/dpu: Increment vsync_cnt before waking up userspace | From | Dmitry Baryshkov <> |
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On 22/06/2022 20:33, Rob Clark wrote: > On Wed, Jun 22, 2022 at 10:24 AM Abhinav Kumar > <quic_abhinavk@quicinc.com> wrote: >> >> >> >> On 6/21/2022 7:38 PM, Stephen Boyd wrote: >>> The 'vsync_cnt' is used to count the number of frames for a crtc. >>> Unfortunately, we increment the count after waking up userspace via >>> dpu_crtc_vblank_callback() calling drm_crtc_handle_vblank(). >>> drm_crtc_handle_vblank() wakes up userspace processes that have called >>> drm_wait_vblank_ioctl(), and if that ioctl is expecting the count to >>> increase it won't. >>> >>> Increment the count before calling into the drm APIs so that we don't >>> have to worry about ordering the increment with anything else in drm. >>> This fixes a software video decode test that fails to see frame counts >>> increase on Trogdor boards. >>> >>> Cc: Mark Yacoub <markyacoub@chromium.org> >>> Cc: Jessica Zhang <quic_jesszhan@quicinc.com> >>> Fixes: 885455d6bf82 ("drm/msm: Change dpu_crtc_get_vblank_counter to use vsync count.") >>> Signed-off-by: Stephen Boyd <swboyd@chromium.org> >> >> This is right, we should increment before drm_crtc_handle_vblank() as >> that will query the vblank counter. This also matches what we do >> downstream, hence >> >> Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com> >> >> One small nit though, shouldnt the fixes tag be >> >> 25fdd5933e4c ("drm/msm: Add SDM845 DPU support") > > *Kinda*.. but the sw vblank counter wasn't used for reporting frame nr > to userspace until 885455d6bf82. You could possibly list both, > perhaps, but 885455d6bf82 is the important one for folks backporting > to stable kernels to be aware of
I'd agree, the original Fixes tag seems good to me.
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
-- With best wishes Dmitry
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