drm: Add get_vblank_timestamp() to struct drm_crtc_funcs

The callback get_vblank_timestamp() is currently located in struct
drm_driver, but really belongs into struct drm_crtc_funcs. Add an
equivalent there. Driver will be converted in separate patches.

The default implementation is drm_calc_vbltimestamp_from_scanoutpos().
The patch adds drm_crtc_vblank_helper_get_vblank_timestamp(), which is
an implementation for the CRTC callback.

v4:
	* more readable code for setting high_prec (Ville, Jani)
v3:
	* use refactored timestamp calculation to minimize duplicated code
	* do more checks for crtc != NULL to support legacy drivers
v2:
	* rename helper to drm_crtc_vblank_helper_get_vblank_timestamp()
	* replace drm_calc_vbltimestamp_from_scanoutpos() with
	  drm_crtc_vblank_helper_get_vblank_timestamp() in docs

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200123135943.24140-4-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 496395324d1fcb337843cb9a4d4db6cb58df0dd2..cc7ef64d35f2b3b003b2abb0f93e0a543d16dc8d 100644 (file)
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -339,7 +339,9 @@ u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc)
        u64 vblank;
        unsigned long flags;
 
-       WARN_ONCE(drm_debug_enabled(DRM_UT_VBL) && !dev->driver->get_vblank_timestamp,
+       WARN_ONCE(drm_debug_enabled(DRM_UT_VBL) &&
+                 !crtc->funcs->get_vblank_timestamp &&
+                 !dev->driver->get_vblank_timestamp,
                  "This function requires support for accurate vblank timestamps.");
 
        spin_lock_irqsave(&dev->vblank_time_lock, flags);
@@ -539,9 +541,9 @@ EXPORT_SYMBOL(drm_crtc_vblank_waitqueue);
  *
  * Calculate and store various constants which are later needed by vblank and
  * swap-completion timestamping, e.g, by
- * drm_calc_vbltimestamp_from_scanoutpos(). They are derived from CRTC's true
- * scanout timing, so they take things like panel scaling or other adjustments
- * into account.
+ * drm_crtc_vblank_helper_get_vblank_timestamp(). They are derived from
+ * CRTC's true scanout timing, so they take things like panel scaling or
+ * other adjustments into account.
  */
 void drm_calc_timestamping_constants(struct drm_crtc *crtc,
                                     const struct drm_display_mode *mode)
@@ -605,8 +607,9 @@ EXPORT_SYMBOL(drm_calc_timestamping_constants);
  *
  * Implements calculation of exact vblank timestamps from given drm_display_mode
  * timings and current video scanout position of a CRTC. This can be directly
- * used as the &drm_driver.get_vblank_timestamp implementation of a kms driver
- * if &drm_crtc_helper_funcs.get_scanout_position is implemented.
+ * used as the &drm_crtc_funcs.get_vblank_timestamp implementation of a kms
+ * driver if &drm_crtc_helper_funcs.get_scanout_position or
+ * &drm_driver.get_scanout_position is implemented.
  *
  * The current implementation only handles standard video modes. For double scan
  * and interlaced modes the driver is supposed to adjust the hardware mode
@@ -802,6 +805,48 @@ drm_crtc_vblank_helper_get_vblank_timestamp_internal(
 }
 EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp_internal);
 
+/**
+ * drm_crtc_vblank_helper_get_vblank_timestamp - precise vblank timestamp
+ *                                               helper
+ * @crtc: CRTC whose vblank timestamp to retrieve
+ * @max_error: Desired maximum allowable error in timestamps (nanosecs)
+ *             On return contains true maximum error of timestamp
+ * @vblank_time: Pointer to time which should receive the 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.
+ *
+ * Implements calculation of exact vblank timestamps from given drm_display_mode
+ * timings and current video scanout position of a CRTC. This can be directly
+ * used as the &drm_crtc_funcs.get_vblank_timestamp implementation of a kms
+ * driver if &drm_crtc_helper_funcs.get_scanout_position is implemented.
+ *
+ * The current implementation only handles standard video modes. For double scan
+ * and interlaced modes the driver is supposed to adjust the hardware mode
+ * (taken from &drm_crtc_state.adjusted mode for atomic modeset drivers) to
+ * match the scanout position reported.
+ *
+ * Note that atomic drivers must call drm_calc_timestamping_constants() before
+ * enabling a CRTC. The atomic helpers already take care of that in
+ * drm_atomic_helper_update_legacy_modeset_state().
+ *
+ * Returns:
+ *
+ * Returns true on success, and false on failure, i.e. when no accurate
+ * timestamp could be acquired.
+ */
+bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc,
+                                                int *max_error,
+                                                ktime_t *vblank_time,
+                                                bool in_vblank_irq)
+{
+       return drm_crtc_vblank_helper_get_vblank_timestamp_internal(
+               crtc, max_error, vblank_time, in_vblank_irq,
+               crtc->helper_private->get_scanout_position, NULL);
+}
+EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp);
+
 /**
  * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
  *                             vblank interval
@@ -827,15 +872,22 @@ static bool
 drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
                          ktime_t *tvblank, bool in_vblank_irq)
 {
+       struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
        bool ret = false;
 
        /* Define requested maximum error on timestamps (nanoseconds). */
        int max_error = (int) drm_timestamp_precision * 1000;
 
        /* Query driver if possible and precision timestamping enabled. */
-       if (dev->driver->get_vblank_timestamp && (max_error > 0))
+       if (crtc && crtc->funcs->get_vblank_timestamp && max_error > 0) {
+               struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
+
+               ret = crtc->funcs->get_vblank_timestamp(crtc, &max_error,
+                                                       tvblank, in_vblank_irq);
+       } else if (dev->driver->get_vblank_timestamp && max_error > 0) {
                ret = dev->driver->get_vblank_timestamp(dev, pipe, &max_error,
                                                        tvblank, in_vblank_irq);
+       }
 
        /* GPU high precision timestamp query unsupported or failed.
         * Return current monotonic/gettimeofday timestamp as best estimate.
@@ -1818,6 +1870,8 @@ done:
 
 static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
 {
+       struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
+       bool high_prec = false;
        struct drm_pending_vblank_event *e, *t;
        ktime_t now;
        u64 seq;
@@ -1840,8 +1894,12 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
                send_vblank_event(dev, e, seq, now);
        }
 
-       trace_drm_vblank_event(pipe, seq, now,
-                       dev->driver->get_vblank_timestamp != NULL);
+       if (crtc && crtc->funcs->get_vblank_timestamp)
+               high_prec = true;
+       else if (dev->driver->get_vblank_timestamp)
+               high_prec = true;
+
+       trace_drm_vblank_event(pipe, seq, now, high_prec);
 }
 
 /**

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;

diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index e398512bfd5fa3f41a6f13fc1a3d00a47e884e31..0afaf58da40dfb856ca916d0c804ea97441ca0c4 100644 (file)
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -459,8 +459,8 @@ struct drm_crtc_helper_funcs {
         * Returns the current display scanout position from a CRTC and an
         * optional accurate ktime_get() timestamp of when the position was
         * measured. Note that this is a helper callback which is only used
-        * if a driver uses drm_calc_vbltimestamp_from_scanoutpos() for the
-        * @drm_driver.get_vblank_timestamp callback.
+        * if a driver uses drm_crtc_vblank_helper_get_vblank_timestamp()
+        * for the @drm_crtc_funcs.get_vblank_timestamp callback.
         *
         * Parameters:
         *

diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h
index fd28741e64ed0b2f65a30da0e1e41eba3cb6ade8..91f8e35d588d9bfc0ab6e209152f13c8953040b8 100644 (file)
--- a/include/drm/drm_vblank.h
+++ b/include/drm/drm_vblank.h
@@ -174,13 +174,13 @@ struct drm_vblank_crtc {
        unsigned int pipe;
        /**
         * @framedur_ns: Frame/Field duration in ns, used by
-        * drm_calc_vbltimestamp_from_scanoutpos() and computed by
+        * drm_crtc_vblank_helper_get_vblank_timestamp() and computed by
         * drm_calc_timestamping_constants().
         */
        int framedur_ns;
        /**
         * @linedur_ns: Line duration in ns, used by
-        * drm_calc_vbltimestamp_from_scanoutpos() and computed by
+        * drm_crtc_vblank_helper_get_vblank_timestamp() and computed by
         * drm_calc_timestamping_constants().
         */
        int linedur_ns;
@@ -190,8 +190,8 @@ struct drm_vblank_crtc {
         *
         * Cache of the current hardware display mode. Only valid when @enabled
         * is set. This is used by helpers like
-        * drm_calc_vbltimestamp_from_scanoutpos(). We can't just access the
-        * hardware mode by e.g. looking at &drm_crtc_state.adjusted_mode,
+        * drm_crtc_vblank_helper_get_vblank_timestamp(). We can't just access
+        * the hardware mode by e.g. looking at &drm_crtc_state.adjusted_mode,
         * because that one is really hard to get from interrupt context.
         */
        struct drm_display_mode hwmode;
@@ -240,6 +240,10 @@ wait_queue_head_t *drm_crtc_vblank_waitqueue(struct drm_crtc *crtc);
 void drm_crtc_set_max_vblank_count(struct drm_crtc *crtc,
                                   u32 max_vblank_count);
 
+/*
+ * Helpers for struct drm_crtc_funcs
+ */
+
 typedef bool (*drm_vblank_get_scanout_position_func)(struct drm_crtc *crtc,
                                                     bool in_vblank_irq,
                                                     int *vpos, int *hpos,
@@ -263,5 +267,9 @@ drm_crtc_vblank_helper_get_vblank_timestamp_internal(struct drm_crtc *crtc,
                                                     bool in_vblank_irq,
                                                     drm_vblank_get_scanout_position_func get_scanout_position,
                                                     drm_vblank_get_scanout_position_legacy_func get_scanout_position_legacy);
+bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc,
+                                                int *max_error,
+                                                ktime_t *vblank_time,
+                                                bool in_vblank_irq);
 
 #endif