drm/i915: add i915_lp_ring_sync helper

This just waits until the hw passed the current ring position with
cmd execution. This slightly changes the existing i915_wait_request
function to make uninterruptible waiting possible - no point in
returning to userspace while mucking around with the overlay, that
piece of hw is just too fragile.

Also replace a magic 0 with the symbolic constant (and kill the then
superflous comment) while I was looking at the code.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/i915_drv.h

@@ -803,6 +803,7 @@ void i915_gem_cleanup_ringbuffer(struct drm_device *dev);
 int i915_gem_do_init(struct drm_device *dev, unsigned long start,
 		     unsigned long end);
 int i915_gem_idle(struct drm_device *dev);
+int i915_lp_ring_sync(struct drm_device *dev);
 int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf);
 int i915_gem_object_set_to_gtt_domain(struct drm_gem_object *obj,
 				      int write);

drivers/gpu/drm/i915/i915_gem.c

@@ -1820,12 +1820,8 @@ i915_gem_retire_work_handler(struct work_struct *work)
 	mutex_unlock(&dev->struct_mutex);
 }
 
-/**
- * Waits for a sequence number to be signaled, and cleans up the
- * request and object lists appropriately for that event.
- */
 static int
-i915_wait_request(struct drm_device *dev, uint32_t seqno)
+i915_do_wait_request(struct drm_device *dev, uint32_t seqno, int interruptible)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	u32 ier;
@@ -1852,10 +1848,15 @@ i915_wait_request(struct drm_device *dev, uint32_t seqno)
 
 		dev_priv->mm.waiting_gem_seqno = seqno;
 		i915_user_irq_get(dev);
+		if (interruptible)
 			ret = wait_event_interruptible(dev_priv->irq_queue,
-					       i915_seqno_passed(i915_get_gem_seqno(dev),
-								 seqno) ||
+				i915_seqno_passed(i915_get_gem_seqno(dev), seqno) ||
+				atomic_read(&dev_priv->mm.wedged));
+		else
+			wait_event(dev_priv->irq_queue,
+				i915_seqno_passed(i915_get_gem_seqno(dev), seqno) ||
 				atomic_read(&dev_priv->mm.wedged));
+
 		i915_user_irq_put(dev);
 		dev_priv->mm.waiting_gem_seqno = 0;
 
@@ -1879,6 +1880,34 @@ i915_wait_request(struct drm_device *dev, uint32_t seqno)
 	return ret;
 }
 
+/**
+ * Waits for a sequence number to be signaled, and cleans up the
+ * request and object lists appropriately for that event.
+ */
+static int
+i915_wait_request(struct drm_device *dev, uint32_t seqno)
+{
+	return i915_do_wait_request(dev, seqno, 1);
+}
+
+/**
+ * Waits for the ring to finish up to the latest request. Usefull for waiting
+ * for flip events, e.g for the overlay support. */
+int i915_lp_ring_sync(struct drm_device *dev)
+{
+	uint32_t seqno;
+	int ret;
+
+	seqno = i915_add_request(dev, NULL, 0);
+
+	if (seqno == 0)
+		return -ENOMEM;
+
+	ret = i915_do_wait_request(dev, seqno, 0);
+	BUG_ON(ret == -ERESTARTSYS);
+	return ret;
+}
+
 static void
 i915_gem_flush(struct drm_device *dev,
 	       uint32_t invalidate_domains,
@@ -1947,7 +1976,7 @@ i915_gem_flush(struct drm_device *dev,
 #endif
 		BEGIN_LP_RING(2);
 		OUT_RING(cmd);
-		OUT_RING(0); /* noop */
+		OUT_RING(MI_NOOP);
 		ADVANCE_LP_RING();
 	}
 }

include/drm/drm_os_linux.h

@@ -123,5 +123,5 @@ do {								\
 	remove_wait_queue(&(queue), &entry);			\
 } while (0)
 
-#define DRM_WAKEUP( queue ) wake_up_interruptible( queue )
+#define DRM_WAKEUP( queue ) wake_up( queue )
 #define DRM_INIT_WAITQUEUE( queue ) init_waitqueue_head( queue )