Re: [PATCH] drm/msm/mdp4: flush vblank event on disable

[Abhinav Kumar]

On 11/27/2023 1:54 PM, Dmitry Baryshkov wrote:
Flush queued events when disabling the crtc. This avoids timeouts when
we come back and wait for dependencies (like the previous frame's
flip_done).

Fixes: c8afe684c95c ("drm/msm: basic KMS driver for snapdragon")
Signed-off-by: Dmitry Baryshkov <dmitry.barysh...@linaro.org>
---
  drivers/gpu/drm/msm/disp/mdp4/mdp4_crtc.c | 9 +++++++++
  1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_crtc.c 
b/drivers/gpu/drm/msm/disp/mdp4/mdp4_crtc.c
index 169f9de4a12a..3100957225a7 100644
--- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_crtc.c
+++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_crtc.c
@@ -269,6 +269,7 @@ static void mdp4_crtc_atomic_disable(struct drm_crtc *crtc,
  {
        struct mdp4_crtc *mdp4_crtc = to_mdp4_crtc(crtc);
        struct mdp4_kms *mdp4_kms = get_kms(crtc);
+       unsigned long flags;
  
  	DBG("%s", mdp4_crtc->name);
  
@@ -281,6 +282,14 @@ static void mdp4_crtc_atomic_disable(struct drm_crtc *crtc,
        mdp_irq_unregister(&mdp4_kms->base, &mdp4_crtc->err);
        mdp4_disable(mdp4_kms);
  
+	if (crtc->state->event && !crtc->state->active) {
+               WARN_ON(mdp4_crtc->event);

Do you need a WARN_ON() here? Just wondering how often this might happen 
and spam.

otherwise LGTM.

+               spin_lock_irqsave(&mdp4_kms->dev->event_lock, flags);
+               drm_crtc_send_vblank_event(crtc, crtc->state->event);
+               crtc->state->event = NULL;
+               spin_unlock_irqrestore(&mdp4_kms->dev->event_lock, flags);
+       }
+
        mdp4_crtc->enabled = false;
  }