4 files changed, 113 insertions, 12 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 92d5605a34d1..5e43d7076789 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -31,6 +31,7 @@
 #include <linux/slab.h>
 #include "drmP.h"
 #include "drm.h"
+#include "intel_drv.h"
 #include "i915_drm.h"
 #include "i915_drv.h"
 
@@ -121,6 +122,54 @@ static int i915_gem_object_list_info(struct seq_file *m, void *data)
 	return 0;
 }
 
+static int i915_gem_pageflip_info(struct seq_file *m, void *data)
+{
+	struct drm_info_node *node = (struct drm_info_node *) m->private;
+	struct drm_device *dev = node->minor->dev;
+	unsigned long flags;
+	struct intel_crtc *crtc;
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, base.head) {
+		const char *pipe = crtc->pipe ? "B" : "A";
+		const char *plane = crtc->plane ? "B" : "A";
+		struct intel_unpin_work *work;
+
+		spin_lock_irqsave(&dev->event_lock, flags);
+		work = crtc->unpin_work;
+		if (work == NULL) {
+			seq_printf(m, "No flip due on pipe %s (plane %s)\n",
+				   pipe, plane);
+		} else {
+			if (!work->pending) {
+				seq_printf(m, "Flip queued on pipe %s (plane %s)\n",
+					   pipe, plane);
+			} else {
+				seq_printf(m, "Flip pending (waiting for vsync) on pipe %s (plane %s)\n",
+					   pipe, plane);
+			}
+			if (work->enable_stall_check)
+				seq_printf(m, "Stall check enabled, ");
+			else
+				seq_printf(m, "Stall check waiting for page flip ioctl, ");
+			seq_printf(m, "%d prepares\n", work->pending);
+
+			if (work->old_fb_obj) {
+				struct drm_i915_gem_object *obj_priv = to_intel_bo(work->old_fb_obj);
+				if(obj_priv)
+					seq_printf(m, "Old framebuffer gtt_offset 0x%08x\n", obj_priv->gtt_offset );
+			}
+			if (work->pending_flip_obj) {
+				struct drm_i915_gem_object *obj_priv = to_intel_bo(work->pending_flip_obj);
+				if(obj_priv)
+					seq_printf(m, "New framebuffer gtt_offset 0x%08x\n", obj_priv->gtt_offset );
+			}
+		}
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+	}
+
+	return 0;
+}
+
 static int i915_gem_request_info(struct seq_file *m, void *data)
 {
 	struct drm_info_node *node = (struct drm_info_node *) m->private;
@@ -777,6 +826,7 @@ static struct drm_info_list i915_debugfs_list[] = {
 	{"i915_gem_active", i915_gem_object_list_info, 0, (void *) ACTIVE_LIST},
 	{"i915_gem_flushing", i915_gem_object_list_info, 0, (void *) FLUSHING_LIST},
 	{"i915_gem_inactive", i915_gem_object_list_info, 0, (void *) INACTIVE_LIST},
+	{"i915_gem_pageflip", i915_gem_pageflip_info, 0},
 	{"i915_gem_request", i915_gem_request_info, 0},
 	{"i915_gem_seqno", i915_gem_seqno_info, 0},
 	{"i915_gem_fence_regs", i915_gem_fence_regs_info, 0},
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 16861b800fee..59457e83b011 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -887,6 +887,49 @@ static void i915_handle_error(struct drm_device *dev, bool wedged)
 	queue_work(dev_priv->wq, &dev_priv->error_work);
 }
 
+static void i915_pageflip_stall_check(struct drm_device *dev, int pipe)
+{
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	struct drm_i915_gem_object *obj_priv;
+	struct intel_unpin_work *work;
+	unsigned long flags;
+	bool stall_detected;
+
+	/* Ignore early vblank irqs */
+	if (intel_crtc == NULL)
+		return;
+
+	spin_lock_irqsave(&dev->event_lock, flags);
+	work = intel_crtc->unpin_work;
+
+	if (work == NULL || work->pending || !work->enable_stall_check) {
+		/* Either the pending flip IRQ arrived, or we're too early. Don't check */
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+		return;
+	}
+
+	/* Potential stall - if we see that the flip has happened, assume a missed interrupt */
+	obj_priv = to_intel_bo(work->pending_flip_obj);
+	if(IS_I965G(dev)) {
+		int dspsurf = intel_crtc->plane == 0 ? DSPASURF : DSPBSURF;
+		stall_detected = I915_READ(dspsurf) == obj_priv->gtt_offset;
+	} else {
+		int dspaddr = intel_crtc->plane == 0 ? DSPAADDR : DSPBADDR;
+		stall_detected = I915_READ(dspaddr) == (obj_priv->gtt_offset +
+							crtc->y * crtc->fb->pitch +
+							crtc->x * crtc->fb->bits_per_pixel/8);
+	}
+
+	spin_unlock_irqrestore(&dev->event_lock, flags);
+
+	if (stall_detected) {
+		DRM_DEBUG_DRIVER("Pageflip stall detected\n");
+		intel_prepare_page_flip(dev, intel_crtc->plane);
+	}
+}
+
 irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
 {
 	struct drm_device *dev = (struct drm_device *) arg;
@@ -1004,15 +1047,19 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
 		if (pipea_stats & vblank_status) {
 			vblank++;
 			drm_handle_vblank(dev, 0);
-			if (!dev_priv->flip_pending_is_done)
+			if (!dev_priv->flip_pending_is_done) {
+				i915_pageflip_stall_check(dev, 0);
 				intel_finish_page_flip(dev, 0);
+			}
 		}
 
 		if (pipeb_stats & vblank_status) {
 			vblank++;
 			drm_handle_vblank(dev, 1);
-			if (!dev_priv->flip_pending_is_done)
+			if (!dev_priv->flip_pending_is_done) {
+				i915_pageflip_stall_check(dev, 1);
 				intel_finish_page_flip(dev, 1);
+			}
 		}
 
 		if ((pipea_stats & PIPE_LEGACY_BLC_EVENT_STATUS) ||
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0b90443f1eb3..1bd0c672ec90 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4864,15 +4864,6 @@ static void intel_crtc_destroy(struct drm_crtc *crtc)
 	kfree(intel_crtc);
 }
 
-struct intel_unpin_work {
-	struct work_struct work;
-	struct drm_device *dev;
-	struct drm_gem_object *old_fb_obj;
-	struct drm_gem_object *pending_flip_obj;
-	struct drm_pending_vblank_event *event;
-	int pending;
-};
-
 static void intel_unpin_work_fn(struct work_struct *__work)
 {
 	struct intel_unpin_work *work =
@@ -4960,7 +4951,8 @@ void intel_prepare_page_flip(struct drm_device *dev, int plane)
 
 	spin_lock_irqsave(&dev->event_lock, flags);
 	if (intel_crtc->unpin_work) {
-		intel_crtc->unpin_work->pending = 1;
+		if ((++intel_crtc->unpin_work->pending) > 1)
+			DRM_ERROR("Prepared flip multiple times\n");
 	} else {
 		DRM_DEBUG_DRIVER("preparing flip with no unpin work?\n");
 	}
@@ -5044,6 +5036,8 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 		ADVANCE_LP_RING();
 	}
 
+	work->enable_stall_check = true;
+
 	/* Offset into the new buffer for cases of shared fbs between CRTCs */
 	offset = crtc->y * fb->pitch + crtc->x * fb->bits_per_pixel/8;
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 0e92aa07b382..ad312ca6b3e5 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -176,6 +176,16 @@ struct intel_crtc {
 #define enc_to_intel_encoder(x) container_of(x, struct intel_encoder, enc)
 #define to_intel_framebuffer(x) container_of(x, struct intel_framebuffer, base)
 
+struct intel_unpin_work {
+	struct work_struct work;
+	struct drm_device *dev;
+	struct drm_gem_object *old_fb_obj;
+	struct drm_gem_object *pending_flip_obj;
+	struct drm_pending_vblank_event *event;
+	int pending;
+	bool enable_stall_check;
+};
+
 struct i2c_adapter *intel_i2c_create(struct drm_device *dev, const u32 reg,
 				     const char *name);
 void intel_i2c_destroy(struct i2c_adapter *adapter);