drm: omapdrm: new vblank and event handling

Rework the crtc event/flip_wait system as follows:

- If we enable a crtc (full modeset), we set omap_crtc->pending and
  register vblank irq.

- If we need to set GO bit (page flip), we do the same but also set the
  GO bit.

- On vblank we unregister the irq, clear the 'pending' flag, send vblank
  event to userspace if crtc->state->event != NULL, and wake up
  'pending_wait' wq.

- In omap_atomic_complete() we wait for the 'pending' flag to get reset
  for all enabled crtcs  using 'pending_wait' wq.

The above ensures that we send the events to userspace in vblank, and
that after the wait in omap_atomic_complete() everything for the
affected crtcs has been completed.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h b/drivers/gpu/drm/omapdrm/omap_drv.h
index 0b7a055..ae2df41 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.h
+++ b/drivers/gpu/drm/omapdrm/omap_drv.h
@@ -147,6 +147,7 @@
 void omap_crtc_pre_uninit(void);
 struct drm_crtc *omap_crtc_init(struct drm_device *dev,
 		struct drm_plane *plane, enum omap_channel channel, int id);
+int omap_crtc_wait_pending(struct drm_crtc *crtc);
 
 struct drm_plane *omap_plane_init(struct drm_device *dev,
 		int id, enum drm_plane_type type);