drm/exynos: add wait_for_vblank callback interface.

Changelog v2:
fixed comments.

Changelog v1:
this interface can be used to make sure that hardware overlay is disabled
to avoid that memory region is accessed by dma after gem buffer was released.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_encoder.c b/drivers/gpu/drm/exynos/exynos_drm_encoder.c
index 08ba62fe2f16..f4531167fda6 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_encoder.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_encoder.c
@@ -430,4 +430,14 @@ void exynos_drm_encoder_plane_disable(struct drm_encoder *encoder, void *data)
 
         if (overlay_ops && overlay_ops->disable)
                 overlay_ops->disable(manager->dev, zpos);
+
+        /*
+         * wait for vblank interrupt
+         * - this makes sure that hardware overlay is disabled to avoid
+         * for the dma accesses to memory after gem buffer was released
+         * because the setting for disabling the overlay will be updated
+         * at vsync.
+         */
+        if (overlay_ops->wait_for_vblank)
+                overlay_ops->wait_for_vblank(manager->dev);
 }