[PATCH 13/13] drm/i915: Optimize out redundant dbuf slice updates

[Shankar, Uma]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Ville
> Syrjala
> Sent: Wednesday, March 27, 2024 11:16 PM
> To: intel-gfx at lists.freedesktop.org
> Subject: [PATCH 13/13] drm/i915: Optimize out redundant dbuf slice updates
> 
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> if the new dbuf slices are a superset of the old dbuf slices then we don't have to
> do anything in intel_dbuf_post_plane_update(). Restructure the code to skip such
> redundant dbuf slice updates. The main benefit is slightly less confusing logs.

Looks Good to me.
Reviewed-by: Uma Shankar <uma.shankar at intel.com>

> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/skl_watermark.c | 27 +++++++++++++-------
>  1 file changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c
> b/drivers/gpu/drm/i915/display/skl_watermark.c
> index 1b48009efe2b..50ec51065118 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> @@ -3788,16 +3788,20 @@ void intel_dbuf_pre_plane_update(struct
> intel_atomic_state *state)
>  		intel_atomic_get_new_dbuf_state(state);
>  	const struct intel_dbuf_state *old_dbuf_state =
>  		intel_atomic_get_old_dbuf_state(state);
> +	u8 old_slices, new_slices;
> 
> -	if (!new_dbuf_state ||
> -	    new_dbuf_state->enabled_slices == old_dbuf_state->enabled_slices)
> +	if (!new_dbuf_state)
> +		return;
> +
> +	old_slices = old_dbuf_state->enabled_slices;
> +	new_slices = old_dbuf_state->enabled_slices |
> +new_dbuf_state->enabled_slices;
> +
> +	if (old_slices == new_slices)
>  		return;
> 
>  	WARN_ON(!new_dbuf_state->base.changed);
> 
> -	gen9_dbuf_slices_update(i915,
> -				old_dbuf_state->enabled_slices |
> -				new_dbuf_state->enabled_slices);
> +	gen9_dbuf_slices_update(i915, new_slices);
>  }
> 
>  void intel_dbuf_post_plane_update(struct intel_atomic_state *state) @@ -
> 3807,15 +3811,20 @@ void intel_dbuf_post_plane_update(struct
> intel_atomic_state *state)
>  		intel_atomic_get_new_dbuf_state(state);
>  	const struct intel_dbuf_state *old_dbuf_state =
>  		intel_atomic_get_old_dbuf_state(state);
> +	u8 old_slices, new_slices;
> 
> -	if (!new_dbuf_state ||
> -	    new_dbuf_state->enabled_slices == old_dbuf_state->enabled_slices)
> +	if (!new_dbuf_state)
> +		return;
> +
> +	old_slices = old_dbuf_state->enabled_slices | new_dbuf_state-
> >enabled_slices;
> +	new_slices = new_dbuf_state->enabled_slices;
> +
> +	if (old_slices == new_slices)
>  		return;
> 
>  	WARN_ON(!new_dbuf_state->base.changed);
> 
> -	gen9_dbuf_slices_update(i915,
> -				new_dbuf_state->enabled_slices);
> +	gen9_dbuf_slices_update(i915, new_slices);
>  }
> 
>  static int skl_watermark_ipc_status_show(struct seq_file *m, void *data)
> --
> 2.43.2