MLK-22653-4 drm/imx: dpu: crtc: Precisely send vbland event if CRTC is active

If CRTC is active, we should send vblank event in vblank
interrupt handler to make sure it's sent precisely.  This
patch caches the event to be sent at dpu_crtc->event in
the ->atomic_enable() and the ->atomic_flush() callbacks
and finally sends it out in dpu_vbl_irq_handler().  Since
we rely on the interrupt handler to send the event, we
call drm_crtc_vblank_get() to get a vblank refcount to
guarantee the interrupt is enabled when caching the event
in dpu_crtc_queue_state_event() and call drm_crtc_vblank_put()
to drop a vblank refcount in the interrupt handler.

Signed-off-by: Liu Ying <victor.liu@nxp.com>
(cherry picked from commit c5f325790615eb16fe5a448e4b0afa122a33c23e)

2 files changed, 32 insertions, 18 deletions

diff --git a/drivers/gpu/drm/imx/dpu/dpu-crtc.c b/drivers/gpu/drm/imx/dpu/dpu-crtc.c
index a6f11ed56e76..eb124d4d32ef 100644
--- a/drivers/gpu/drm/imx/dpu/dpu-crtc.c
+++ b/drivers/gpu/drm/imx/dpu/dpu-crtc.c
@@ -45,6 +45,20 @@ alloc_dpu_plane_states(struct dpu_crtc *dpu_crtc)
 	return states;
 }
 
+static void dpu_crtc_queue_state_event(struct drm_crtc *crtc)
+{
+	struct dpu_crtc *dpu_crtc = to_dpu_crtc(crtc);
+
+	spin_lock_irq(&crtc->dev->event_lock);
+	if (crtc->state->event) {
+		WARN_ON(drm_crtc_vblank_get(crtc));
+		WARN_ON(dpu_crtc->event);
+		dpu_crtc->event = crtc->state->event;
+		crtc->state->event = NULL;
+	}
+	spin_unlock_irq(&crtc->dev->event_lock);
+}
+
 struct dpu_plane_state **
 crtc_state_get_dpu_plane_states(struct drm_crtc_state *state)
 {
@@ -240,13 +254,7 @@ static void dpu_crtc_atomic_enable(struct drm_crtc *crtc,
 		disable_irq(aux_dpu_crtc->dec_shdld_irq);
 	}
 
-	if (crtc->state->event) {
-		spin_lock_irq(&crtc->dev->event_lock);
-		drm_crtc_send_vblank_event(crtc, crtc->state->event);
-		spin_unlock_irq(&crtc->dev->event_lock);
-
-		crtc->state->event = NULL;
-	}
+	dpu_crtc_queue_state_event(crtc);
 
 	if (dcstate->use_pc) {
 		framegen_wait_for_secondary_syncup(dpu_crtc->m_fg);
@@ -313,13 +321,12 @@ static void dpu_crtc_atomic_disable(struct drm_crtc *crtc,
 
 	drm_crtc_vblank_off(crtc);
 
+	spin_lock_irq(&crtc->dev->event_lock);
 	if (crtc->state->event && !crtc->state->active) {
-		spin_lock_irq(&crtc->dev->event_lock);
 		drm_crtc_send_vblank_event(crtc, crtc->state->event);
-		spin_unlock_irq(&crtc->dev->event_lock);
-
 		crtc->state->event = NULL;
 	}
+	spin_unlock_irq(&crtc->dev->event_lock);
 }
 
 static void dpu_drm_crtc_reset(struct drm_crtc *crtc)
@@ -431,8 +438,18 @@ static const struct drm_crtc_funcs dpu_crtc_funcs = {
 static irqreturn_t dpu_vbl_irq_handler(int irq, void *dev_id)
 {
 	struct dpu_crtc *dpu_crtc = dev_id;
+	struct drm_crtc *crtc = &dpu_crtc->base;
+	unsigned long flags;
 
-	drm_crtc_handle_vblank(&dpu_crtc->base);
+	drm_crtc_handle_vblank(crtc);
+
+	spin_lock_irqsave(&crtc->dev->event_lock, flags);
+	if (dpu_crtc->event) {
+		drm_crtc_send_vblank_event(crtc, dpu_crtc->event);
+		dpu_crtc->event = NULL;
+		drm_crtc_vblank_put(crtc);
+	}
+	spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
 
 	return IRQ_HANDLED;
 }
@@ -772,13 +789,7 @@ static void dpu_crtc_atomic_flush(struct drm_crtc *crtc,
 			}
 		}
 
-		if (crtc->state->event) {
-			spin_lock_irq(&crtc->dev->event_lock);
-			drm_crtc_send_vblank_event(crtc, crtc->state->event);
-			spin_unlock_irq(&crtc->dev->event_lock);
-
-			crtc->state->event = NULL;
-		}
+		dpu_crtc_queue_state_event(crtc);
 	} else if (!crtc->state->active) {
 		if (old_dcstate->use_pc) {
 			if (extdst_is_master(ed)) {
diff --git a/drivers/gpu/drm/imx/dpu/dpu-crtc.h b/drivers/gpu/drm/imx/dpu/dpu-crtc.h
index 2e3a283cb68c..c4be53926e2b 100644
--- a/drivers/gpu/drm/imx/dpu/dpu-crtc.h
+++ b/drivers/gpu/drm/imx/dpu/dpu-crtc.h
@@ -15,6 +15,7 @@
 #ifndef _DPU_CRTC_H_
 #define _DPU_CRTC_H_
 
+#include <drm/drm_vblank.h>
 #include <video/dpu.h>
 #include "dpu-plane.h"
 #include "imx-drm.h"
@@ -77,6 +78,8 @@ struct dpu_crtc {
 	struct completion	crc_shdld_done;
 	struct completion	aux_crc_done;
 
+	struct drm_pending_vblank_event *event;
+
 	u32			crc_red;
 	u32			crc_green;
 	u32			crc_blue;