drm: add drm_send_vblank_event() helper (v5)

A helper that drivers can use to send vblank event after a pageflip.
If the driver doesn't support proper vblank irq based time/seqn then
just pass -1 for the pipe # to get do_gettimestamp() behavior (since
there are a lot of drivers that don't use drm_vblank_count_and_time())

Also an internal send_vblank_event() helper for the various other code
paths within drm_irq that also need to send vblank events.

v1: original
v2: add back 'vblwait->reply.sequence = seq' which should not have
    been deleted
v3: add WARN_ON() in case lock is not held and comments
v4: use WARN_ON_SMP() instead to fix issue with !SMP && !DEBUG_SPINLOCK
    as pointed out by Marcin Slusarz
v5: update docbook
Signed-off-by: Rob Clark <rob@ti.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Documentation/DocBook/drm.tmpl

@@ -1141,23 +1141,13 @@ int max_width, max_height;</synopsis>
             the <methodname>page_flip</methodname> operation will be called with a
             non-NULL <parameter>event</parameter> argument pointing to a
             <structname>drm_pending_vblank_event</structname> instance. Upon page
-            flip completion the driver must fill the
-            <parameter>event</parameter>::<structfield>event</structfield>
-            <structfield>sequence</structfield>, <structfield>tv_sec</structfield>
-            and <structfield>tv_usec</structfield> fields with the associated
-            vertical blanking count and timestamp, add the event to the
-            <parameter>drm_file</parameter> list of events to be signaled, and wake
-            up any waiting process. This can be performed with
+            flip completion the driver must call <methodname>drm_send_vblank_event</methodname>
+            to fill in the event and send to wake up any waiting processes.
+            This can be performed with
             <programlisting><![CDATA[
-            struct timeval now;
-
-            event->event.sequence = drm_vblank_count_and_time(..., &now);
-            event->event.tv_sec = now.tv_sec;
-            event->event.tv_usec = now.tv_usec;
-
             spin_lock_irqsave(&dev->event_lock, flags);
-            list_add_tail(&event->base.link, &event->base.file_priv->event_list);
-            wake_up_interruptible(&event->base.file_priv->event_wait);
+            ...
+            drm_send_vblank_event(dev, pipe, event);
             spin_unlock_irqrestore(&dev->event_lock, flags);
             ]]></programlisting>
           </para>

drivers/gpu/drm/drm_irq.c

@@ -802,6 +802,46 @@ u32 drm_vblank_count_and_time(struct drm_device *dev, int crtc,
 }
 EXPORT_SYMBOL(drm_vblank_count_and_time);
 
+static void send_vblank_event(struct drm_device *dev,
+		struct drm_pending_vblank_event *e,
+		unsigned long seq, struct timeval *now)
+{
+	WARN_ON_SMP(!spin_is_locked(&dev->event_lock));
+	e->event.sequence = seq;
+	e->event.tv_sec = now->tv_sec;
+	e->event.tv_usec = now->tv_usec;
+
+	list_add_tail(&e->base.link,
+		      &e->base.file_priv->event_list);
+	wake_up_interruptible(&e->base.file_priv->event_wait);
+	trace_drm_vblank_event_delivered(e->base.pid, e->pipe,
+					 e->event.sequence);
+}
+
+/**
+ * drm_send_vblank_event - helper to send vblank event after pageflip
+ * @dev: DRM device
+ * @crtc: CRTC in question
+ * @e: the event to send
+ *
+ * Updates sequence # and timestamp on event, and sends it to userspace.
+ * Caller must hold event lock.
+ */
+void drm_send_vblank_event(struct drm_device *dev, int crtc,
+		struct drm_pending_vblank_event *e)
+{
+	struct timeval now;
+	unsigned int seq;
+	if (crtc >= 0) {
+		seq = drm_vblank_count_and_time(dev, crtc, &now);
+	} else {
+		seq = 0;
+		do_gettimeofday(&now);
+	}
+	send_vblank_event(dev, e, seq, &now);
+}
+EXPORT_SYMBOL(drm_send_vblank_event);
+
 /**
  * drm_update_vblank_count - update the master vblank counter
  * @dev: DRM device
@@ -936,6 +976,13 @@ void drm_vblank_put(struct drm_device *dev, int crtc)
 }
 EXPORT_SYMBOL(drm_vblank_put);
 
+/**
+ * drm_vblank_off - disable vblank events on a CRTC
+ * @dev: DRM device
+ * @crtc: CRTC in question
+ *
+ * Caller must hold event lock.
+ */
 void drm_vblank_off(struct drm_device *dev, int crtc)
 {
 	struct drm_pending_vblank_event *e, *t;
@@ -955,15 +1002,9 @@ void drm_vblank_off(struct drm_device *dev, int crtc)
 		DRM_DEBUG("Sending premature vblank event on disable: \
 			  wanted %d, current %d\n",
 			  e->event.sequence, seq);
-
-		e->event.sequence = seq;
-		e->event.tv_sec = now.tv_sec;
-		e->event.tv_usec = now.tv_usec;
+		list_del(&e->base.link);
 		drm_vblank_put(dev, e->pipe);
-		list_move_tail(&e->base.link, &e->base.file_priv->event_list);
-		wake_up_interruptible(&e->base.file_priv->event_wait);
-		trace_drm_vblank_event_delivered(e->base.pid, e->pipe,
-						 e->event.sequence);
+		send_vblank_event(dev, e, seq, &now);
 	}
 
 	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
@@ -1107,15 +1148,9 @@ static int drm_queue_vblank_event(struct drm_device *dev, int pipe,
 
 	e->event.sequence = vblwait->request.sequence;
 	if ((seq - vblwait->request.sequence) <= (1 << 23)) {
-		e->event.sequence = seq;
-		e->event.tv_sec = now.tv_sec;
-		e->event.tv_usec = now.tv_usec;
 		drm_vblank_put(dev, pipe);
-		list_add_tail(&e->base.link, &e->base.file_priv->event_list);
-		wake_up_interruptible(&e->base.file_priv->event_wait);
+		send_vblank_event(dev, e, seq, &now);
 		vblwait->reply.sequence = seq;
-		trace_drm_vblank_event_delivered(current->pid, pipe,
-						 vblwait->request.sequence);
 	} else {
 		/* drm_handle_vblank_events will call drm_vblank_put */
 		list_add_tail(&e->base.link, &dev->vblank_event_list);
@@ -1256,14 +1291,9 @@ static void drm_handle_vblank_events(struct drm_device *dev, int crtc)
 		DRM_DEBUG("vblank event on %d, current %d\n",
 			  e->event.sequence, seq);
 
-		e->event.sequence = seq;
-		e->event.tv_sec = now.tv_sec;
-		e->event.tv_usec = now.tv_usec;
+		list_del(&e->base.link);
 		drm_vblank_put(dev, e->pipe);
-		list_move_tail(&e->base.link, &e->base.file_priv->event_list);
-		wake_up_interruptible(&e->base.file_priv->event_wait);
-		trace_drm_vblank_event_delivered(e->base.pid, e->pipe,
-						 e->event.sequence);
+		send_vblank_event(dev, e, seq, &now);
 	}
 
 	spin_unlock_irqrestore(&dev->event_lock, flags);

include/drm/drmP.h

@@ -1431,6 +1431,8 @@ extern int drm_vblank_wait(struct drm_device *dev, unsigned int *vbl_seq);
 extern u32 drm_vblank_count(struct drm_device *dev, int crtc);
 extern u32 drm_vblank_count_and_time(struct drm_device *dev, int crtc,
 				     struct timeval *vblanktime);
+extern void drm_send_vblank_event(struct drm_device *dev, int crtc,
+				     struct drm_pending_vblank_event *e);
 extern bool drm_handle_vblank(struct drm_device *dev, int crtc);
 extern int drm_vblank_get(struct drm_device *dev, int crtc);
 extern void drm_vblank_put(struct drm_device *dev, int crtc);