[Intel-gfx] [PATCH v2 5/5] drm/i915: Allow cdclk squasher to be reconfigured live

[Kahola, Mika]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Mika
> Kahola
> Sent: Friday, November 19, 2021 3:14 PM
> To: intel-gfx at lists.freedesktop.org
> Subject: [Intel-gfx] [PATCH v2 5/5] drm/i915: Allow cdclk squasher to be
> reconfigured live
> 
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Supposedly we should be able to change the cdclk squasher waveform even
> when many pipes are active. Make it so.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Reviewed-by: Mika Kahola <mika.kahola at intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_cdclk.c | 40 ++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c
> b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 5fcb393079f7..075ad6055765 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -1951,6 +1951,25 @@ static bool intel_cdclk_can_crawl(struct
> drm_i915_private *dev_priv,
>  		a->ref == b->ref;
>  }
> 
> +static bool intel_cdclk_can_squash(struct drm_i915_private *dev_priv,
> +				   const struct intel_cdclk_config *a,
> +				   const struct intel_cdclk_config *b) {
> +	/*
> +	 * FIXME should store a bit more state in intel_cdclk_config
> +	 * to differentiate squasher vs. cd2x divider properly. For
> +	 * the moment all platforms with squasher use a fixed cd2x
> +	 * divider.
> +	 */
> +	if (!has_cdclk_squasher(dev_priv))
> +		return false;
> +
> +	return a->cdclk != b->cdclk &&
> +		a->vco != 0 &&
> +		a->vco == b->vco &&
> +		a->ref == b->ref;
> +}
> +
>  /**
>   * intel_cdclk_needs_modeset - Determine if changong between the CDCLK
>   *                             configurations requires a modeset on all pipes
> @@ -1988,7 +2007,17 @@ static bool intel_cdclk_can_cd2x_update(struct
> drm_i915_private *dev_priv,
>  	if (DISPLAY_VER(dev_priv) < 10 && !IS_BROXTON(dev_priv))
>  		return false;
> 
> +	/*
> +	 * FIXME should store a bit more state in intel_cdclk_config
> +	 * to differentiate squasher vs. cd2x divider properly. For
> +	 * the moment all platforms with squasher use a fixed cd2x
> +	 * divider.
> +	 */
> +	if (has_cdclk_squasher(dev_priv))
> +		return false;
> +
>  	return a->cdclk != b->cdclk &&
> +		a->vco != 0 &&
>  		a->vco == b->vco &&
>  		a->ref == b->ref;
>  }
> @@ -2672,9 +2701,14 @@ int intel_modeset_calc_cdclk(struct
> intel_atomic_state *state)
>  			pipe = INVALID_PIPE;
>  	}
> 
> -	if (intel_cdclk_can_crawl(dev_priv,
> -				  &old_cdclk_state->actual,
> -				  &new_cdclk_state->actual)) {
> +	if (intel_cdclk_can_squash(dev_priv,
> +				   &old_cdclk_state->actual,
> +				   &new_cdclk_state->actual)) {
> +		drm_dbg_kms(&dev_priv->drm,
> +			    "Can change cdclk via squasher\n");
> +	} else if (intel_cdclk_can_crawl(dev_priv,
> +					 &old_cdclk_state->actual,
> +					 &new_cdclk_state->actual)) {
>  		drm_dbg_kms(&dev_priv->drm,
>  			    "Can change cdclk via crawl\n");
>  	} else if (pipe != INVALID_PIPE) {
> --
> 2.27.0