[Intel-gfx] [PATCH v2 10/16] drm/i915: Wait for watermark updates to finish before disabling a pipe

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

After we've disabled the planes, it seems like a good idea wait for
the vblank driven watermark updates to finish before we turn off the
vblank interrupts and eventually the entire pipe.

v2: Rebase and s/intel_crtc/crtc/

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h      |  1 +
 drivers/gpu/drm/i915/intel_display.c |  2 ++
 drivers/gpu/drm/i915/intel_drv.h     |  1 +
 drivers/gpu/drm/i915/intel_pm.c      | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 5b1404e..1fe0cac 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1554,6 +1554,7 @@ struct drm_i915_private {
 		struct mutex mutex;
 
 		struct work_struct work;
+		wait_queue_head_t wait;
 	} wm;
 
 	struct i915_runtime_pm pm;
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 5bf1633..ca362db 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3960,6 +3960,8 @@ static void intel_crtc_disable_planes(struct drm_crtc *crtc)
 	intel_disable_planes(crtc);
 	intel_disable_primary_hw_plane(dev_priv, plane, pipe);
 
+	ilk_wm_synchronize(intel_crtc);
+
 	drm_vblank_off(dev, pipe);
 }
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 1ec4379..5ad7ad5 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1021,6 +1021,7 @@ void intel_program_watermarks_pre(struct intel_crtc *crtc,
 				  const struct intel_crtc_wm_config *config);
 void intel_program_watermarks_post(struct intel_crtc *crtc,
 				   const struct intel_crtc_wm_config *config);
+void ilk_wm_synchronize(struct intel_crtc *crtc);
 
 
 /* intel_sdvo.c */
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 13366b7..1c072cd 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2812,6 +2812,7 @@ static bool ilk_pending_watermarks_ready(struct intel_crtc *crtc)
 
 static bool ilk_refresh_pending_watermarks(struct drm_device *dev)
 {
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_crtc *crtc;
 	bool changed = false;
 
@@ -2833,6 +2834,9 @@ static bool ilk_refresh_pending_watermarks(struct drm_device *dev)
 		changed = true;
 	}
 
+	if (changed)
+		wake_up_all(&dev_priv->wm.wait);
+
 	return changed;
 }
 
@@ -3029,6 +3033,33 @@ static void ilk_wm_cancel(struct intel_crtc *crtc)
 	}
 }
 
+void ilk_wm_synchronize(struct intel_crtc *crtc)
+{
+	struct drm_device *dev = crtc->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	enum pipe pipe = crtc->pipe;
+	unsigned long timeout = msecs_to_jiffies(100);
+
+	wait_event_timeout(dev_priv->wm.wait, !crtc->wm.dirty, timeout);
+
+	mutex_lock(&dev_priv->wm.mutex);
+
+	spin_lock_irq(&crtc->wm.lock);
+
+	WARN(crtc->wm.dirty, "pipe %c watermark updates failed to complete\n",
+	     pipe_name(pipe));
+
+	/* clean up if something is left behind */
+	ilk_wm_cancel(crtc);
+
+	spin_unlock_irq(&crtc->wm.lock);
+
+	/* pending update (if any) got cancelled */
+	crtc->wm.pending = crtc->wm.active;
+
+	mutex_unlock(&dev_priv->wm.mutex);
+}
+
 static int ilk_update_primary_wm(struct intel_crtc *crtc,
 				 struct intel_crtc_wm_config *config)
 {
@@ -6736,6 +6767,7 @@ void intel_init_pm(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	mutex_init(&dev_priv->wm.mutex);
+	init_waitqueue_head(&dev_priv->wm.wait);
 	INIT_WORK(&dev_priv->wm.work, ilk_watermark_work);
 
 	if (HAS_FBC(dev)) {
-- 
1.8.5.5