[PATCH v7 10/15] drm/vblank: Add helper to get next vblank time

[Mario Kleiner]

LGTM. This one is

Reviewed-by: Mario Kleiner <mario.kleiner.de at gmail.com>

-mario


On Mon, Feb 27, 2023 at 8:36 PM Rob Clark <robdclark at gmail.com> wrote:

> From: Rob Clark <robdclark at chromium.org>
>
> Will be used in the next commit to set a deadline on fences that an
> atomic update is waiting on.
>
> v2: Calculate time at *start* of vblank period, not end
> v3: Fix kbuild complaints
>
> Signed-off-by: Rob Clark <robdclark at chromium.org>
> ---
>  drivers/gpu/drm/drm_vblank.c | 53 ++++++++++++++++++++++++++++++------
>  include/drm/drm_vblank.h     |  1 +
>  2 files changed, 45 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index 2ff31717a3de..299fa2a19a90 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -844,10 +844,9 @@ bool
> drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc,
>  EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp);
>
>  /**
> - * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
> - *                             vblank interval
> - * @dev: DRM device
> - * @pipe: index of CRTC whose vblank timestamp to retrieve
> + * drm_crtc_get_last_vbltimestamp - retrieve raw timestamp for the most
> + *                                  recent vblank interval
> + * @crtc: CRTC whose vblank timestamp to retrieve
>   * @tvblank: Pointer to target time which should receive the timestamp
>   * @in_vblank_irq:
>   *     True when called from drm_crtc_handle_vblank().  Some drivers
> @@ -865,10 +864,9 @@
> EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp);
>   * True if timestamp is considered to be very precise, false otherwise.
>   */
>  static bool
> -drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
> -                         ktime_t *tvblank, bool in_vblank_irq)
> +drm_crtc_get_last_vbltimestamp(struct drm_crtc *crtc, 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). */
> @@ -876,8 +874,6 @@ drm_get_last_vbltimestamp(struct drm_device *dev,
> unsigned int pipe,
>
>         /* Query driver if possible and precision timestamping enabled. */
>         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);
>         }
> @@ -891,6 +887,15 @@ drm_get_last_vbltimestamp(struct drm_device *dev,
> unsigned int pipe,
>         return ret;
>  }
>
> +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);
> +
> +       return drm_crtc_get_last_vbltimestamp(crtc, tvblank,
> in_vblank_irq);
> +}
> +
>  /**
>   * drm_crtc_vblank_count - retrieve "cooked" vblank counter value
>   * @crtc: which counter to retrieve
> @@ -980,6 +985,36 @@ u64 drm_crtc_vblank_count_and_time(struct drm_crtc
> *crtc,
>  }
>  EXPORT_SYMBOL(drm_crtc_vblank_count_and_time);
>
> +/**
> + * drm_crtc_next_vblank_start - 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 start of the next vblank period,
> + * based on time of previous vblank and frame duration
> + */
> +int drm_crtc_next_vblank_start(struct drm_crtc *crtc, ktime_t *vblanktime)
> +{
> +       unsigned int pipe = drm_crtc_index(crtc);
> +       struct drm_vblank_crtc *vblank = &crtc->dev->vblank[pipe];
> +       struct drm_display_mode *mode = &vblank->hwmode;
> +       u64 vblank_start;
> +
> +       if (!vblank->framedur_ns || !vblank->linedur_ns)
> +               return -EINVAL;
> +
> +       if (!drm_crtc_get_last_vbltimestamp(crtc, vblanktime, false))
> +               return -EINVAL;
> +
> +       vblank_start = DIV_ROUND_DOWN_ULL(
> +                       (u64)vblank->framedur_ns * mode->crtc_vblank_start,
> +                       mode->crtc_vtotal);
> +       *vblanktime  = ktime_add(*vblanktime, ns_to_ktime(vblank_start));
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(drm_crtc_next_vblank_start);
> +
>  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..7f3957943dd1 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_start(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,
> --
> 2.39.1
>
>
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