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@xxxxxxxxxxxx>
Cc: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
Fixes: 885455d6bf82 ("drm/msm: Change dpu_crtc_get_vblank_counter to use vsync count.")
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
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@xxxxxxxxxxx>
One small nit though, shouldnt the fixes tag be
25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
This code has been this way since that commit itself.
---
drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index 3a462e327e0e..a1b8c4592943 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -1251,12 +1251,13 @@ static void dpu_encoder_vblank_callback(struct drm_encoder *drm_enc,
DPU_ATRACE_BEGIN("encoder_vblank_callback");
dpu_enc = to_dpu_encoder_virt(drm_enc);
+ atomic_inc(&phy_enc->vsync_cnt);
+
spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
if (dpu_enc->crtc)
dpu_crtc_vblank_callback(dpu_enc->crtc);
spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
- atomic_inc(&phy_enc->vsync_cnt);
DPU_ATRACE_END("encoder_vblank_callback");
}
base-commit: f2906aa863381afb0015a9eb7fefad885d4e5a56
