From: Rob Clark <robdclark@xxxxxxxxxxxx>
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
---
drivers/gpu/drm/drm_vblank.c | 31 +++++++++++++++++++++++++++++++
include/drm/drm_vblank.h | 1 +
2 files changed, 32 insertions(+)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 3417e1ac7918..88c824c294dc 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -980,6 +980,37 @@ u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
}
EXPORT_SYMBOL(drm_crtc_vblank_count_and_time);
+/**
+ * drm_crtc_next_vblank_time - calculate the time of the next vblank
+ * @crtc: the crtc for which to calculate next vblank time
+ * @vblanktime: pointer to time to receive the next vblank timestamp.
+ *
+ * Calculate the expected time of the next vblank based on time of previous
+ * vblank and frame duration
+ */
+int drm_crtc_next_vblank_time(struct drm_crtc *crtc, ktime_t *vblanktime)
+{
+ unsigned int pipe = drm_crtc_index(crtc);
+ struct drm_vblank_crtc *vblank = &crtc->dev->vblank[pipe];
+ u64 count;
+
+ if (!vblank->framedur_ns)
+ return -EINVAL;
+
+ count = drm_vblank_count_and_time(crtc->dev, pipe, vblanktime);
+
+ /*
+ * If we don't get a valid count, then we probably also don't
+ * have a valid time:
+ */
+ if (!count)
+ return -EINVAL;
+
+ *vblanktime = ktime_add(*vblanktime, ns_to_ktime(vblank->framedur_ns));
+
+ return 0;
+}
+
static void send_vblank_event(struct drm_device *dev,
struct drm_pending_vblank_event *e,
u64 seq, ktime_t now)
diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h
index 733a3e2d1d10..a63bc2c92f3c 100644
--- a/include/drm/drm_vblank.h
+++ b/include/drm/drm_vblank.h
@@ -230,6 +230,7 @@ bool drm_dev_has_vblank(const struct drm_device *dev);
u64 drm_crtc_vblank_count(struct drm_crtc *crtc);
u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
ktime_t *vblanktime);
+int drm_crtc_next_vblank_time(struct drm_crtc *crtc, ktime_t *vblanktime);
void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
struct drm_pending_vblank_event *e);
void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
--
2.31.1
