drm/tilcdc: Recover from sync lost error flood by resetting the LCDC

Recover from sync lost error flood by resetting the LCDC instead of
turning off the SYNC_LOST error IRQ. When LCDC starves on limited
memory bandwidth it may sometimes result an error situation when the
picture may have shifted couple of pixels to right and SYNC_LOST
interrupt is generated on every frame. LCDC main reset recovers from
this situation and causes a brief blanking on the screen.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Tested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

1 files changed, 25 insertions, 1 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 0d09acce4916..c7873493f506 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -55,6 +55,7 @@ struct tilcdc_crtc {
 
         int sync_lost_count;
         bool frame_intact;
+        struct work_struct recover_work;
 };
 #define to_tilcdc_crtc(x) container_of(x, struct tilcdc_crtc, base)
 
@@ -252,6 +253,25 @@ static bool tilcdc_crtc_is_on(struct drm_crtc *crtc)
         return crtc->state && crtc->state->enable && crtc->state->active;
 }
 
+static void tilcdc_crtc_recover_work(struct work_struct *work)
+{
+        struct tilcdc_crtc *tilcdc_crtc =
+                container_of(work, struct tilcdc_crtc, recover_work);
+        struct drm_crtc *crtc = &tilcdc_crtc->base;
+
+        dev_info(crtc->dev->dev, "%s: Reset CRTC", __func__);
+
+        drm_modeset_lock_crtc(crtc, NULL);
+
+        if (!tilcdc_crtc_is_on(crtc))
+                goto out;
+
+        tilcdc_crtc_disable(crtc);
+        tilcdc_crtc_enable(crtc);
+out:
+        drm_modeset_unlock_crtc(crtc);
+}
+
 static void tilcdc_crtc_destroy(struct drm_crtc *crtc)
 {
         struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
@@ -838,9 +858,12 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
                         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);
+                                dev_err(dev->dev, "%s(0x%08x): Sync lost flood detected, recovering", __func__, stat);
+                                queue_work(system_wq,
+                                           &tilcdc_crtc->recover_work);
                                 tilcdc_write(dev, LCDC_INT_ENABLE_CLR_REG,
                                              LCDC_SYNC_LOST);
+                                tilcdc_crtc->sync_lost_count = 0;
                         }
                 }
 
@@ -880,6 +903,7 @@ struct drm_crtc *tilcdc_crtc_create(struct drm_device *dev)
                         "unref", unref_worker);
 
         spin_lock_init(&tilcdc_crtc->irq_lock);
+        INIT_WORK(&tilcdc_crtc->recover_work, tilcdc_crtc_recover_work);
 
         ret = drm_crtc_init_with_planes(dev, crtc,
                                         &tilcdc_crtc->primary,