drm: Add a debug node for vblank state.

Signed-off-by: Eric Anholt <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/drm_irq.c

···
 		 dev->num_crtcs, DRM_MEM_DRIVER);
 	drm_free(dev->last_vblank, sizeof(*dev->last_vblank) * dev->num_crtcs,
 		 DRM_MEM_DRIVER);
+	drm_free(dev->last_vblank_wait,
+		 sizeof(*dev->last_vblank_wait) * dev->num_crtcs,
+		 DRM_MEM_DRIVER);
 	drm_free(dev->vblank_inmodeset, sizeof(*dev->vblank_inmodeset) *
 		 dev->num_crtcs, DRM_MEM_DRIVER);
 
···
 
 	dev->last_vblank = drm_calloc(num_crtcs, sizeof(u32), DRM_MEM_DRIVER);
 	if (!dev->last_vblank)
+		goto err;
+
+	dev->last_vblank_wait = drm_calloc(num_crtcs, sizeof(u32),
+					   DRM_MEM_DRIVER);
+	if (!dev->last_vblank_wait)
 		goto err;
 
 	dev->vblank_inmodeset = drm_calloc(num_crtcs, sizeof(int),
···
 	} else {
 		DRM_DEBUG("waiting on vblank count %d, crtc %d\n",
 			  vblwait->request.sequence, crtc);
+		dev->last_vblank_wait[crtc] = vblwait->request.sequence;
 		DRM_WAIT_ON(ret, dev->vbl_queue[crtc], 3 * DRM_HZ,
 			    ((drm_vblank_count(dev, crtc)
 			      - vblwait->request.sequence) <= (1 << 23)));

drivers/gpu/drm/drm_proc.c

···
 			   int request, int *eof, void *data);
 static int drm_bufs_info(char *buf, char **start, off_t offset,
 			 int request, int *eof, void *data);
+static int drm_vblank_info(char *buf, char **start, off_t offset,
+			   int request, int *eof, void *data);
 static int drm_gem_name_info(char *buf, char **start, off_t offset,
 			     int request, int *eof, void *data);
 static int drm_gem_object_info(char *buf, char **start, off_t offset,
···
 	{"clients", drm_clients_info, 0},
 	{"queues", drm_queues_info, 0},
 	{"bufs", drm_bufs_info, 0},
+	{"vblank", drm_vblank_info, 0},
 	{"gem_names", drm_gem_name_info, DRIVER_GEM},
 	{"gem_objects", drm_gem_object_info, DRIVER_GEM},
 #if DRM_DEBUG_CODE
···
 
 	mutex_lock(&dev->struct_mutex);
 	ret = drm__bufs_info(buf, start, offset, request, eof, data);
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
+}
+
+/**
+ * Called when "/proc/dri/.../vblank" is read.
+ *
+ * \param buf output buffer.
+ * \param start start of output data.
+ * \param offset requested start offset.
+ * \param request requested number of bytes.
+ * \param eof whether there is no more data to return.
+ * \param data private data.
+ * \return number of written bytes.
+ */
+static int drm__vblank_info(char *buf, char **start, off_t offset, int request,
+			  int *eof, void *data)
+{
+	struct drm_minor *minor = (struct drm_minor *) data;
+	struct drm_device *dev = minor->dev;
+	int len = 0;
+	int crtc;
+
+	if (offset > DRM_PROC_LIMIT) {
+		*eof = 1;
+		return 0;
+	}
+
+	*start = &buf[offset];
+	*eof = 0;
+
+	for (crtc = 0; crtc < dev->num_crtcs; crtc++) {
+		DRM_PROC_PRINT("CRTC %d enable:     %d\n",
+			       crtc, atomic_read(&dev->vblank_refcount[crtc]));
+		DRM_PROC_PRINT("CRTC %d counter:    %d\n",
+			       crtc, drm_vblank_count(dev, crtc));
+		DRM_PROC_PRINT("CRTC %d last wait:  %d\n",
+			       crtc, dev->last_vblank_wait[crtc]);
+		DRM_PROC_PRINT("CRTC %d in modeset: %d\n",
+			       crtc, dev->vblank_inmodeset[crtc]);
+	}
+
+	if (len > request + offset)
+		return request;
+	*eof = 1;
+	return len - offset;
+}
+
+/**
+ * Simply calls _vblank_info() while holding the drm_device::struct_mutex lock.
+ */
+static int drm_vblank_info(char *buf, char **start, off_t offset, int request,
+			 int *eof, void *data)
+{
+	struct drm_minor *minor = (struct drm_minor *) data;
+	struct drm_device *dev = minor->dev;
+	int ret;
+
+	mutex_lock(&dev->struct_mutex);
+	ret = drm__vblank_info(buf, start, offset, request, eof, data);
 	mutex_unlock(&dev->struct_mutex);
 	return ret;
 }

include/drm/drmP.h

···
 	int *vblank_enabled;            /* so we don't call enable more than
 					   once per disable */
 	int *vblank_inmodeset;          /* Display driver is setting mode */
+	u32 *last_vblank_wait;		/* Last vblank seqno waited per CRTC */
 	struct timer_list vblank_disable_timer;
 
 	u32 max_vblank_count;           /**< size of vblank counter register */