Re: [Intel-gfx] [PATCH 4/8] drm/i915: Introduce skl_ddb_entry_for_slices()

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Tue, Oct 27, 2020 at 10:39:51PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Generalize icl_get_first_dbuf_slice_offset() into something that
> just gives us the start+end of the dbuf chunk covered by the
> specified slices as a standard ddb entry. Initial idea was to use
> it during readout as well, but we shall see.
> 
> Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_pm.c | 55 +++++++++++----------------------
>  1 file changed, 18 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 8083785237ba..e4917454ec07 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4042,25 +4042,23 @@ static int intel_dbuf_slice_size(struct drm_i915_private *dev_priv)
>  		INTEL_INFO(dev_priv)->num_supported_dbuf_slices;
>  }
>  
> -/*
> - * Calculate initial DBuf slice offset, based on slice size
> - * and mask(i.e if slice size is 1024 and second slice is enabled
> - * offset would be 1024)
> - */
> -static unsigned int
> -icl_get_first_dbuf_slice_offset(u32 dbuf_slice_mask,
> -				u32 slice_size,
> -				u32 ddb_size)
> +static void
> +skl_ddb_entry_for_slices(struct drm_i915_private *dev_priv, u8 slice_mask,
> +			 struct skl_ddb_entry *ddb)
>  {
> -	unsigned int offset = 0;
> +	int slice_size = intel_dbuf_slice_size(dev_priv);
>  
> -	if (!dbuf_slice_mask)
> -		return 0;
> +	if (!slice_mask) {
> +		ddb->start = 0;
> +		ddb->end = 0;
> +		return;
> +	}
>  
> -	offset = (ffs(dbuf_slice_mask) - 1) * slice_size;
> +	ddb->start = (ffs(slice_mask) - 1) * slice_size;
> +	ddb->end = fls(slice_mask) * slice_size;
>  
> -	WARN_ON(offset >= ddb_size);
> -	return offset;
> +	WARN_ON(ddb->start >= ddb->end);
> +	WARN_ON(ddb->end > intel_dbuf_size(dev_priv));
>  }
>  
>  u32 skl_ddb_dbuf_slice_mask(struct drm_i915_private *dev_priv,
> @@ -4131,12 +4129,10 @@ skl_ddb_get_pipe_allocation_limits(struct drm_i915_private *dev_priv,
>  	const struct intel_dbuf_state *old_dbuf_state =
>  		intel_atomic_get_old_dbuf_state(intel_state);
>  	u8 active_pipes = new_dbuf_state->active_pipes;
> -	u16 ddb_size;
> +	struct skl_ddb_entry ddb_slices;
>  	u32 ddb_range_size;
>  	u32 i;
>  	u32 dbuf_slice_mask;
> -	u32 offset;
> -	u32 slice_size;
>  	u32 total_slice_mask;
>  	u32 start, end;
>  	int ret;
> @@ -4149,9 +4145,6 @@ skl_ddb_get_pipe_allocation_limits(struct drm_i915_private *dev_priv,
>  		return 0;
>  	}
>  
> -	ddb_size = intel_dbuf_size(dev_priv);
> -	slice_size = intel_dbuf_slice_size(dev_priv);
> -
>  	/*
>  	 * If the state doesn't change the active CRTC's or there is no
>  	 * modeset request, then there's no need to recalculate;
> @@ -4177,20 +4170,8 @@ skl_ddb_get_pipe_allocation_limits(struct drm_i915_private *dev_priv,
>  	 */
>  	dbuf_slice_mask = skl_compute_dbuf_slices(for_crtc, active_pipes);
>  
> -	/*
> -	 * Figure out at which DBuf slice we start, i.e if we start at Dbuf S2
> -	 * and slice size is 1024, the offset would be 1024
> -	 */
> -	offset = icl_get_first_dbuf_slice_offset(dbuf_slice_mask,
> -						 slice_size, ddb_size);
> -
> -	/*
> -	 * Figure out total size of allowed DBuf slices, which is basically
> -	 * a number of allowed slices for that pipe multiplied by slice size.
> -	 * Inside of this
> -	 * range ddb entries are still allocated in proportion to display width.
> -	 */
> -	ddb_range_size = hweight8(dbuf_slice_mask) * slice_size;
> +	skl_ddb_entry_for_slices(dev_priv, dbuf_slice_mask, &ddb_slices);
> +	ddb_range_size = skl_ddb_entry_size(&ddb_slices);
>  
>  	total_slice_mask = dbuf_slice_mask;
>  	for_each_new_intel_crtc_in_state(intel_state, crtc, crtc_state, i) {
> @@ -4247,8 +4228,8 @@ skl_ddb_get_pipe_allocation_limits(struct drm_i915_private *dev_priv,
>  	start = ddb_range_size * weight_before_pipe / total_weight;
>  	end = ddb_range_size * (weight_before_pipe + pipe_weight) / total_weight;
>  
> -	alloc->start = offset + start;
> -	alloc->end = offset + end;
> +	alloc->start = ddb_slices.start + start;
> +	alloc->end = ddb_slices.start + end;
>  
>  	drm_dbg_kms(&dev_priv->drm,
>  		    "[CRTC:%d:%s] dbuf slices 0x%x, ddb (%d - %d), active pipes 0x%x\n",
> -- 
> 2.26.2
> 
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