drm/i915/psr: Add PSR pause/resume reference count

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.

v3: Incorporate changes missing from v2
v2: Add drm_warn for detecting possible unbalanced pause/resume

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250328080623.1183669-1-jouni.hogander@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 7d9cc430a6b8b54e37f7396b9a6b7a4d4b78f1a8..367b53a9eae2ab7ab126d80ae9f635c6a2471fbd 100644 (file)
--- 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 c4be3f46511f75ec66fe81447e4cdf7845b27cf0..55414fa55b126ac517fd75d89c841fa513a0b6c5 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -2014,7 +2014,7 @@ 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
@@ -2199,7 +2199,6 @@ 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))
@@ -2212,12 +2211,10 @@ 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);
 
@@ -2233,6 +2230,7 @@ void intel_psr_pause(struct intel_dp *intel_dp)
  */
 void intel_psr_resume(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))
@@ -2240,13 +2238,18 @@ void intel_psr_resume(struct intel_dp *intel_dp)
 
        mutex_lock(&psr->lock);
 
-       if (!psr->paused)
-               goto unlock;
+       if (!psr->enabled)
+               goto out;
 
-       psr->paused = false;
-       intel_psr_activate(intel_dp);
+       if (!psr->pause_counter) {
+               drm_warn(display->drm, "Unbalanced PSR pause/resume!\n");
+               goto out;
+       }
 
-unlock:
+       if (--intel_dp->psr.pause_counter == 0)
+               intel_psr_activate(intel_dp);
+
+out:
        mutex_unlock(&psr->lock);
 }
 
@@ -3298,7 +3301,7 @@ 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 ||