drm/tilcdc: Disable sync lost interrupt if it fires on every frame

Disable the sync lost interrupt if it fires on every frame for 50
consecutive frames in a row. This is relatively sure sign of the sync
lost interrupt being stuck and firing on every frame even if the
display otherwise appears to work OK.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 5ee22c6b37e8..248e3ea7568c 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -43,6 +43,9 @@ struct tilcdc_crtc {
 
         /* Only set if an external encoder is connected */
         bool simulate_vesa_sync;
+
+        int sync_lost_count;
+        bool frame_intact;
 };
 #define to_tilcdc_crtc(x) container_of(x, struct tilcdc_crtc, base)
 
@@ -662,6 +665,8 @@ out:
         pm_runtime_put_sync(dev->dev);
 }
 
+#define SYNC_LOST_COUNT_LIMIT 50
+
 irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
 {
         struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
@@ -707,6 +712,11 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
 
                         spin_unlock_irqrestore(&dev->event_lock, flags);
                 }
+
+                if (tilcdc_crtc->frame_intact)
+                        tilcdc_crtc->sync_lost_count = 0;
+                else
+                        tilcdc_crtc->frame_intact = true;
         }
 
         if (priv->rev == 2) {
@@ -717,9 +727,18 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
                 tilcdc_write(dev, LCDC_END_OF_INT_IND_REG, 0);
         }
 
-        if (stat & LCDC_SYNC_LOST)
+        if (stat & LCDC_SYNC_LOST) {
                 dev_err_ratelimited(dev->dev, "%s(0x%08x): Sync lost",
                                     __func__, stat);
+                tilcdc_crtc->frame_intact = false;
+                if (tilcdc_crtc->sync_lost_count++ > SYNC_LOST_COUNT_LIMIT) {
+                        dev_err(dev->dev,
+                                "%s(0x%08x): Sync lost flood detected, disabling the interrupt",
+                                __func__, stat);
+                        tilcdc_write(dev, LCDC_INT_ENABLE_CLR_REG,
+                                     LCDC_SYNC_LOST);
+                }
+        }
 
         if (stat & LCDC_FIFO_UNDERFLOW)
                 dev_err_ratelimited(dev->dev, "%s(0x%08x): FIFO underfow",