On Wed, Jan 15, 2020 at 01:16:34PM +0100, Thomas Zimmermann wrote:
> 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.
>
> 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@xxxxxxx>
> ---
> drivers/gpu/drm/drm_vblank.c | 236 +++++++++++++++++++++--
> include/drm/drm_crtc.h | 46 ++++-
> include/drm/drm_modeset_helper_vtables.h | 4 +-
> include/drm/drm_vblank.h | 26 ++-
> 4 files changed, 292 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index abb085c67d82..1b7af316e6a5 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -333,7 +333,9 @@ 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);
> @@ -511,9 +513,9 @@ 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)
> @@ -577,8 +579,9 @@ 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
> @@ -742,15 +745,22 @@ 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->funcs->get_vblank_timestamp && (max_error > 0)) {
Could drop the superfluous parens while at it.
Are all drivers utilizing this guaranteed to have the crtc here?
> + 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.
> @@ -1059,11 +1069,19 @@ EXPORT_SYMBOL(drm_crtc_vblank_get);
>
> static bool __vblank_disable_immediate(struct drm_device *dev, unsigned int pipe)
> {
> + struct drm_crtc *crtc;
> +
> if (!dev->vblank_disable_immediate)
> return false;
> - if (!dev->driver->get_vblank_timestamp)
> - return false;
> - return true;
> +
> + crtc = drm_crtc_from_index(dev, pipe);
> + if (crtc && crtc->funcs->get_vblank_timestamp)
Here you are expecting that the crtc might be NULL.
> + return true;
> +
> + if (dev->driver->get_vblank_timestamp)
> + return true;
> +
> + return false;
> }
>
> static void drm_vblank_put(struct drm_device *dev, unsigned int pipe)
> @@ -1742,9 +1760,11 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data,
>
> static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
> {
> + struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
> struct drm_pending_vblank_event *e, *t;
> ktime_t now;
> u64 seq;
> + bool high_prec;
>
> assert_spin_locked(&dev->event_lock);
>
> @@ -1764,8 +1784,10 @@ 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);
> + high_prec = crtc->funcs->get_vblank_timestamp ||
> + dev->driver->get_vblank_timestamp;
Here again assuming the crtc can't be NULL.
> +
> + trace_drm_vblank_event(pipe, seq, now, high_prec);
> }
>
> /**
> @@ -2020,3 +2042,193 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data,
> kfree(e);
> return ret;
> }
> +
> +/*
> + * Helpers for struct drm_crtc_funcs
> + */
> +
> +/**
> + * drm_crtc_vblank_helper_get_vblank_timestamp_internal - precise vblank
> + * timestamp helper
> + * @dev: DRM device
> + * @pipe: index of 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.
> + * @get_scanout_position:
> + * Callback function to retrieve the scanout position. See
> + * @struct drm_crtc_helper_funcs.get_scanout_position.
> + *
> + * Implements calculation of exact vblank timestamps from given drm_display_mode
> + * timings and current video scanout position of a CRTC.
> + *
> + * 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_internal(
> + struct drm_crtc *crtc, int *max_error, ktime_t *vblank_time,
> + bool in_vblank_irq,
> + bool (*get_scanout_position)(struct drm_crtc *crtc,
> + bool in_vblank_irq, int *vpos, int *hpos,
> + ktime_t *stime, ktime_t *etime,
> + const struct drm_display_mode *mode))
> +{
> + struct drm_device *dev = crtc->dev;
> + unsigned int pipe = crtc->index;
> + struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
> + struct timespec64 ts_etime, ts_vblank_time;
> + ktime_t stime, etime;
> + bool vbl_status;
> + const struct drm_display_mode *mode;
> + int vpos, hpos, i;
> + int delta_ns, duration_ns;
> +
> + if (pipe >= dev->num_crtcs) {
> + DRM_ERROR("Invalid crtc %u\n", pipe);
> + return false;
> + }
> +
> + /* Scanout position query not supported? Should not happen. */
> + if (!get_scanout_position) {
> + DRM_ERROR("Called from CRTC w/o get_scanout_position()!?\n");
> + return false;
> + }
> +
> + if (drm_drv_uses_atomic_modeset(dev))
> + mode = &vblank->hwmode;
> + else
> + mode = &crtc->hwmode;
> +
> + /* If mode timing undefined, just return as no-op:
> + * Happens during initial modesetting of a crtc.
> + */
> + if (mode->crtc_clock == 0) {
> + DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n", pipe);
> + WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev));
> + return false;
> + }
> +
> + /* Get current scanout position with system timestamp.
> + * Repeat query up to DRM_TIMESTAMP_MAXRETRIES times
> + * if single query takes longer than max_error nanoseconds.
> + *
> + * This guarantees a tight bound on maximum error if
> + * code gets preempted or delayed for some reason.
> + */
> + for (i = 0; i < DRM_TIMESTAMP_MAXRETRIES; i++) {
> + /*
> + * Get vertical and horizontal scanout position vpos, hpos,
> + * and bounding timestamps stime, etime, pre/post query.
> + */
> + vbl_status = get_scanout_position(crtc, in_vblank_irq, &vpos,
> + &hpos, &stime, &etime, mode);
> +
> + /* Return as no-op if scanout query unsupported or failed. */
> + if (!vbl_status) {
> + DRM_DEBUG("crtc %u : scanoutpos query failed.\n",
> + pipe);
> + return false;
> + }
> +
> + /* Compute uncertainty in timestamp of scanout position query. */
> + duration_ns = ktime_to_ns(etime) - ktime_to_ns(stime);
> +
> + /* Accept result with < max_error nsecs timing uncertainty. */
> + if (duration_ns <= *max_error)
> + break;
> + }
> +
> + /* Noisy system timing? */
> + if (i == DRM_TIMESTAMP_MAXRETRIES) {
> + DRM_DEBUG("crtc %u: Noisy timestamp %d us > %d us [%d reps].\n",
> + pipe, duration_ns/1000, *max_error/1000, i);
> + }
> +
> + /* Return upper bound of timestamp precision error. */
> + *max_error = duration_ns;
> +
> + /* Convert scanout position into elapsed time at raw_time query
> + * since start of scanout at first display scanline. delta_ns
> + * can be negative if start of scanout hasn't happened yet.
> + */
> + delta_ns = div_s64(1000000LL * (vpos * mode->crtc_htotal + hpos),
> + mode->crtc_clock);
> +
> + /* Subtract time delta from raw timestamp to get final
> + * vblank_time timestamp for end of vblank.
> + */
> + *vblank_time = ktime_sub_ns(etime, delta_ns);
> +
> + if (!drm_debug_enabled(DRM_UT_VBL))
> + return true;
> +
> + ts_etime = ktime_to_timespec64(etime);
> + ts_vblank_time = ktime_to_timespec64(*vblank_time);
> +
> + DRM_DEBUG_VBL("crtc %u : v p(%d,%d)@ %lld.%06ld -> %lld.%06ld [e %d us, %d rep]\n",
> + pipe, hpos, vpos,
> + (u64)ts_etime.tv_sec, ts_etime.tv_nsec / 1000,
> + (u64)ts_vblank_time.tv_sec, ts_vblank_time.tv_nsec / 1000,
> + duration_ns / 1000, i);
> +
> + return true;
> +}
> +EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp_internal);
This looks like copy paste from the current thing. Why are you
duplicating the entire function instead of refactoring what
we already have?
> +
> +/**
> + * 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);
> +}
> +EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp);
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 5e9b15a0e8c5..db46abbbf4e7 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -867,6 +867,47 @@ 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);
> };
>
> /**
> @@ -974,11 +1015,12 @@ 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 e398512bfd5f..0afaf58da40d 100644
> --- 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 c16c44052b3d..248fbd5de177 100644
> --- 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;
> @@ -238,4 +238,22 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc,
> 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
> + */
> +
> +bool
> +drm_crtc_vblank_helper_get_vblank_timestamp_internal(
> + struct drm_crtc *crtc, int *max_error, ktime_t *vblank_time,
> + bool in_vblank_irq,
> + bool (*get_scanout_position)(struct drm_crtc *crtc,
> + bool in_vblank_irq, int *vpos, int *hpos,
> + ktime_t *stime, ktime_t *etime,
> + const struct drm_display_mode *mode));
Ugly alignment. Could maybe add a typedef for the function pointer if it
otherwise gets super horrible with proper alignment.
> +bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc,
> + int *max_error,
> + ktime_t *vblank_time,
> + bool in_vblank_irq);
> +
> #endif
> --
> 2.24.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Ville Syrjälä
Intel
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