Commit 7fe3f0d1 authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

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: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200123135943.24140-4-tzimmermann@suse.de
parent f1e2b637

drivers/gpu/drm/drm_vblank.c

+67 −9
Original line number Diff line number Diff line
@@ -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);

}



/**

include/drm/drm_crtc.h

+44 −2
Original line number Diff line number Diff line
@@ -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;

include/drm/drm_modeset_helper_vtables.h

+2 −2
Original line number Diff line number Diff line
@@ -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:

	 *

include/drm/drm_vblank.h

+12 −4
Original line number Diff line number Diff line
@@ -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

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