drm: Add get_vblank_timestamp() to struct drm_crtc_funcs

[linux-block.git] / include / drm / drm_crtc.h

diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 6bef2f41d4d70a928b35a01ccec46b93b8c6a4d1..59b51a09cae6b8683e0b9abafe9560c145d74dac 100644 (file)
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -887,6 +887,47 @@ struct drm_crtc_funcs {
         * new drivers as the replacement of &drm_driver.disable_vblank hook.
         */
        void (*disable_vblank)(struct drm_crtc *crtc);
+
+       /**
+        * @get_vblank_timestamp:
+        *
+        * Called by drm_get_last_vbltimestamp(). Should return a precise
+        * timestamp when the most recent vblank interval ended or will end.
+        *
+        * Specifically, the timestamp in @vblank_time should correspond as
+        * closely as possible to the time when the first video scanline of
+        * the video frame after the end of vblank will start scanning out,
+        * the time immediately after end of the vblank interval. If the
+        * @crtc is currently inside vblank, this will be a time in the future.
+        * If the @crtc is currently scanning out a frame, this will be the
+        * past start time of the current scanout. This is meant to adhere
+        * to the OpenML OML_sync_control extension specification.
+        *
+        * Parameters:
+        *
+        * crtc:
+        *     CRTC for which timestamp should be returned.
+        * max_error:
+        *     Maximum allowable timestamp error in nanoseconds.
+        *     Implementation should strive to provide timestamp
+        *     with an error of at most max_error nanoseconds.
+        *     Returns true upper bound on error for timestamp.
+        * vblank_time:
+        *     Target location for returned vblank timestamp.
+        * in_vblank_irq:
+        *     True when called from drm_crtc_handle_vblank().  Some drivers
+        *     need to apply some workarounds for gpu-specific vblank irq quirks
+        *     if flag is set.
+        *
+        * Returns:
+        *
+        * True on success, false on failure, which means the core should
+        * fallback to a simple timestamp taken in drm_crtc_handle_vblank().
+        */
+       bool (*get_vblank_timestamp)(struct drm_crtc *crtc,
+                                    int *max_error,
+                                    ktime_t *vblank_time,
+                                    bool in_vblank_irq);
 };
 
 /**
@@ -994,11 +1035,12 @@ struct drm_crtc {
         * Programmed mode in hw, after adjustments for encoders, crtc, panel
         * scaling etc. Should only be used by legacy drivers, for high
         * precision vblank timestamps in
-        * drm_calc_vbltimestamp_from_scanoutpos().
+        * drm_crtc_vblank_helper_get_vblank_timestamp().
         *
         * Note that atomic drivers should not use this, but instead use
         * &drm_crtc_state.adjusted_mode. And for high-precision timestamps
-        * drm_calc_vbltimestamp_from_scanoutpos() used &drm_vblank_crtc.hwmode,
+        * drm_crtc_vblank_helper_get_vblank_timestamp() used
+        * &drm_vblank_crtc.hwmode,
         * which is filled out by calling drm_calc_timestamping_constants().
         */
        struct drm_display_mode hwmode;