From: Rob Clark robdclark@chromium.org
Signed-off-by: Rob Clark robdclark@chromium.org --- 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,