[RFC PATCH 2/3] drm/msm: keep the commit vblank reference through completion

[Zhang Jiaxi]

From: Jiaxi Zhang <z1529105815@xxxxxxxxxxx>

The synchronous and async commit paths acquire a vblank reference before
flush, then release it before calling complete_commit. The DPU completion
callback reaches dpu_crtc_complete_commit and _dpu_crtc_complete_flip, which
sends the pending page-flip event with drm_crtc_send_vblank_event. That
function consumes the vblank counter and timestamp.

Release the commit's reference after the completion callback returns.
There is then no zero-reference interval between the commit's wait_flush
and its remaining event delivery. This matters when immediate vblank
IRQ disabling is enabled. Keep the existing enable_commit/disable_commit
clock lifetime and CRTC locking, in both commit paths; no callback or wait
is moved outside that lifetime.

This is a reference-lifetime correction, not an assertion that completion
waits for another TE interrupt. It does not impose an always-on IRQ policy
or change the encoder's transfer-completion mechanism.

Signed-off-by: Jiaxi Zhang <z1529105815@xxxxxxxxxxx>

---
diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
--- a/drivers/gpu/drm/msm/msm_atomic.c
+++ b/drivers/gpu/drm/msm/msm_atomic.c
@@ -91,9 +91,8 @@
 	kms->funcs->wait_flush(kms, crtc_mask);
 	trace_msm_atomic_wait_flush_finish(crtc_mask);
 
+	kms->funcs->complete_commit(kms, crtc_mask);
 	vblank_put(kms, crtc_mask);
-
-	kms->funcs->complete_commit(kms, crtc_mask);
 	unlock_crtcs(kms, crtc_mask);
 	kms->funcs->disable_commit(kms);
 
@@ -310,10 +309,9 @@
 	kms->funcs->wait_flush(kms, crtc_mask);
 	trace_msm_atomic_wait_flush_finish(crtc_mask);
 
-	vblank_put(kms, crtc_mask);
-
 	lock_crtcs(kms, crtc_mask);
 	kms->funcs->complete_commit(kms, crtc_mask);
+	vblank_put(kms, crtc_mask);
 	unlock_crtcs(kms, crtc_mask);
 	kms->funcs->disable_commit(kms);