Re: [PATCH 1/8] drm/i915/skl: Make 'end' of the DDB allocation entry exclusive

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Oct 14, 2014 at 05:30:59PM +0100, Damien Lespiau wrote:
> Ville suggested that we should use the same semantics as C arrays to
> reduce the number of those pesky +1/-1 in the allocation code.
> 
> This patch leaves the debugfs file as is, showing the internal DDB
> allocation structure, not the values written in the registers.
> 
> Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h |  4 ++--
>  drivers/gpu/drm/i915/intel_pm.c | 28 +++++++++++++++++++---------
>  2 files changed, 21 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 14be1dc..0320698 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1414,7 +1414,7 @@ struct ilk_wm_values {
>  };
>  
>  struct skl_ddb_entry {
> -	uint16_t start, end;	/* in number of blocks */
> +	uint16_t start, end;	/* in number of blocks, 'end' is exclusive */
>  };
>  
>  static inline uint16_t skl_ddb_entry_size(const struct skl_ddb_entry *entry)
> @@ -1423,7 +1423,7 @@ static inline uint16_t skl_ddb_entry_size(const struct skl_ddb_entry *entry)
>  	if (entry->end == 0)
>  		return 0;

We can now drop the special case for end==0. The rest looks good so

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

>  
> -	return entry->end - entry->start + 1;
> +	return entry->end - entry->start;
>  }
>  
>  static inline bool skl_ddb_entry_equal(const struct skl_ddb_entry *e1,
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 2a41ae8..016b54e 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3038,7 +3038,7 @@ skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
>  
>  	pipe_size = ddb_size / config->num_pipes_active;
>  	alloc->start = nth_active_pipe * ddb_size / config->num_pipes_active;
> -	alloc->end = alloc->start + pipe_size - 1;
> +	alloc->end = alloc->start + pipe_size;
>  }
>  
>  static unsigned int skl_cursor_allocation(const struct intel_wm_config *config)
> @@ -3053,6 +3053,8 @@ static void skl_ddb_entry_init_from_hw(struct skl_ddb_entry *entry, u32 reg)
>  {
>  	entry->start = reg & 0x3ff;
>  	entry->end = (reg >> 16) & 0x3ff;
> +	if (entry->end)
> +		entry->end += 1;
>  }
>  
>  void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv,
> @@ -3129,7 +3131,7 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
>  	}
>  
>  	cursor_blocks = skl_cursor_allocation(config);
> -	ddb->cursor[pipe].start = alloc.end - cursor_blocks + 1;
> +	ddb->cursor[pipe].start = alloc.end - cursor_blocks;
>  	ddb->cursor[pipe].end = alloc.end;
>  
>  	alloc_size -= cursor_blocks;
> @@ -3163,7 +3165,7 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
>  				       total_data_rate);
>  
>  		ddb->plane[pipe][plane].start = start;
> -		ddb->plane[pipe][plane].end = start + plane_blocks - 1;
> +		ddb->plane[pipe][plane].end = start + plane_blocks;
>  
>  		start += plane_blocks;
>  	}
> @@ -3467,6 +3469,15 @@ static void skl_compute_wm_results(struct drm_device *dev,
>  	r->wm_linetime[pipe] = p_wm->linetime;
>  }
>  
> +static void skl_ddb_entry_write(struct drm_i915_private *dev_priv, uint32_t reg,
> +				const struct skl_ddb_entry *entry)
> +{
> +	if (entry->end)
> +		I915_WRITE(reg, (entry->end - 1) << 16 | entry->start);
> +	else
> +		I915_WRITE(reg, 0);
> +}
> +
>  static void skl_write_wm_values(struct drm_i915_private *dev_priv,
>  				const struct skl_wm_values *new)
>  {
> @@ -3494,13 +3505,12 @@ static void skl_write_wm_values(struct drm_i915_private *dev_priv,
>  			I915_WRITE(CUR_WM_TRANS(pipe), new->cursor_trans[pipe]);
>  
>  			for (i = 0; i < intel_num_planes(crtc); i++)
> -				I915_WRITE(PLANE_BUF_CFG(pipe, i),
> -					   new->ddb.plane[pipe][i].end << 16 |
> -					   new->ddb.plane[pipe][i].start);
> +				skl_ddb_entry_write(dev_priv,
> +						    PLANE_BUF_CFG(pipe, i),
> +						    &new->ddb.plane[pipe][i]);
>  
> -			I915_WRITE(CUR_BUF_CFG(pipe),
> -				   new->ddb.cursor[pipe].end << 16 |
> -				   new->ddb.cursor[pipe].start);
> +			skl_ddb_entry_write(dev_priv, CUR_BUF_CFG(pipe),
> +					    &new->ddb.cursor[pipe]);
>  		}
>  	}
>  }
> -- 
> 1.8.3.1
> 
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-- 
Ville Syrjälä
Intel OTC
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