[PATCH] drm/i915/psr: Add PSR pause/resume reference count

[Jouni Högander <jouni.hogander@xxxxxxxxx>]

We have now seen this:

<4> [2120.434153] i915 0000:00:02.0: [drm] drm_WARN_ON(psr->paused)
<4> [2120.434196] WARNING: CPU: 3 PID: 4430 at drivers/gpu/drm/i915/display/intel_psr.c:2227 intel_psr_pause+0x16e/0x180 [i915]

Comment for drm_WARN_ON(display->drm, psr->paused) in intel_psr_pause says:

"If we ever hit this, we will need to add refcount to pause/resume"

This patch is implementing PSR pause/resume refcount.

Signed-off-by: Jouni Högander <jouni.hogander@xxxxxxxxx>
---
 .../drm/i915/display/intel_display_types.h    |  2 +-
 drivers/gpu/drm/i915/display/intel_psr.c      | 26 +++++++++----------
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 99a6fd2900b9c..65c808bba1c6c 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1620,7 +1620,7 @@ struct intel_psr {
 	bool sink_support;
 	bool source_support;
 	bool enabled;
-	bool paused;
+	int pause_counter;
 	enum pipe pipe;
 	enum transcoder transcoder;
 	bool active;
diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 4e938bad808cc..4d4ecf7555b66 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -2024,7 +2024,7 @@ static void intel_psr_enable_locked(struct intel_dp *intel_dp,
 
 	intel_psr_enable_source(intel_dp, crtc_state);
 	intel_dp->psr.enabled = true;
-	intel_dp->psr.paused = false;
+	intel_dp->psr.pause_counter = 0;
 
 	/*
 	 * Link_ok is sticky and set here on PSR enable. We can assume link
@@ -2210,7 +2210,6 @@ void intel_psr_disable(struct intel_dp *intel_dp,
  */
 void intel_psr_pause(struct intel_dp *intel_dp)
 {
-	struct intel_display *display = to_intel_display(intel_dp);
 	struct intel_psr *psr = &intel_dp->psr;
 
 	if (!CAN_PSR(intel_dp) && !CAN_PANEL_REPLAY(intel_dp))
@@ -2223,12 +2222,10 @@ void intel_psr_pause(struct intel_dp *intel_dp)
 		return;
 	}
 
-	/* If we ever hit this, we will need to add refcount to pause/resume */
-	drm_WARN_ON(display->drm, psr->paused);
-
-	intel_psr_exit(intel_dp);
-	intel_psr_wait_exit_locked(intel_dp);
-	psr->paused = true;
+	if (intel_dp->psr.pause_counter++ == 0) {
+		intel_psr_exit(intel_dp);
+		intel_psr_wait_exit_locked(intel_dp);
+	}
 
 	mutex_unlock(&psr->lock);
 
@@ -2251,13 +2248,14 @@ void intel_psr_resume(struct intel_dp *intel_dp)
 
 	mutex_lock(&psr->lock);
 
-	if (!psr->paused)
-		goto unlock;
+	if (!psr->enabled) {
+		mutex_unlock(&psr->lock);
+		return;
+	}
 
-	psr->paused = false;
-	intel_psr_activate(intel_dp);
+	if (--intel_dp->psr.pause_counter == 0)
+		intel_psr_activate(intel_dp);
 
-unlock:
 	mutex_unlock(&psr->lock);
 }
 
@@ -3322,7 +3320,7 @@ void intel_psr_flush(struct intel_display *display,
 		 * we have to ensure that the PSR is not activated until
 		 * intel_psr_resume() is called.
 		 */
-		if (intel_dp->psr.paused)
+		if (intel_dp->psr.pause_counter)
 			goto unlock;
 
 		if (origin == ORIGIN_FLIP ||
-- 
2.43.0