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>

2 files changed, 27 insertions, 0 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exynos/exynos_drm_drv.h
index 24c45d86bab0..eec77aa6962f 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h
@@ -37,6 +37,20 @@
 #define MAX_FB_BUFFER   4
 #define DEFAULT_ZPOS    -1
 
+#define _wait_for(COND, MS) ({ \
+        unsigned long timeout__ = jiffies + msecs_to_jiffies(MS);       \
+        int ret__ = 0;                                                  \
+        while (!(COND)) {                                               \
+                if (time_after(jiffies, timeout__)) {                   \
+                        ret__ = -ETIMEDOUT;                             \
+                        break;                                          \
+                }                                                       \
+        }                                                               \
+        ret__;                                                          \
+})
+
+#define wait_for(COND, MS) _wait_for(COND, MS)
+
 struct drm_device;
 struct exynos_drm_overlay;
 struct drm_connector;
@@ -61,6 +75,8 @@ enum exynos_drm_output_type {
  * @commit: apply hardware specific overlay data to registers.
  * @enable: enable hardware specific overlay.
  * @disable: disable hardware specific overlay.
+ * @wait_for_vblank: wait for vblank interrupt to make sure that
+ *      hardware overlay is disabled.
  */
 struct exynos_drm_overlay_ops {
         void (*mode_set)(struct device *subdrv_dev,
@@ -68,6 +84,7 @@ struct exynos_drm_overlay_ops {
         void (*commit)(struct device *subdrv_dev, int zpos);
         void (*enable)(struct device *subdrv_dev, int zpos);
         void (*disable)(struct device *subdrv_dev, int zpos);
+        void (*wait_for_vblank)(struct device *subdrv_dev);
 };
 
 /*
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);
 }