On Wed, Aug 19, 2015 at 06:02:22PM -0700, Chandra Konduru wrote:
> Properly allocate min blocks per hw requirements.
> 
> Signed-off-by: Chandra Konduru <chandra.kond...@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c |   39 
> +++++++++++++++++++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index fff0c22..da3046f 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -2959,6 +2959,41 @@ skl_get_total_relative_data_rate(struct intel_crtc 
> *intel_crtc,
>       return total_data_rate;
>  }
>  
> +static uint16_t
> +skl_dbuf_min_alloc(const struct intel_plane_wm_parameters *p, int y_plane)

bool y_plane

In general I dislike the fact that the code treats Y as the special case
instead of CbCr. The oppostire would be far more natural IMO, and,
I believe, would result in less checks in the code all around. Althouh
I think in general we should just pass around the format and plane index.

> +{
> +     uint16_t min_alloc;
> +
> +     /* For packed formats, no y-plane, return 0 */
> +     if (y_plane && !p->y_bytes_per_pixel)
> +             return 0;
> +
> +

Extra line.

> +     if (p->tiling == I915_FORMAT_MOD_Y_TILED ||
> +         p->tiling == I915_FORMAT_MOD_Yf_TILED) {
> +             uint32_t min_scanlines = 8;
> +             uint8_t bytes_per_pixel =
> +                     y_plane ? p->y_bytes_per_pixel : p->bytes_per_pixel;
> +
> +             switch (bytes_per_pixel) {
> +             case 1:
> +                     min_scanlines = 32;
> +                     break;
> +             case 2:
> +                     min_scanlines = 16;
> +                     break;
> +             case 8:
> +                     WARN(1, "Unsupported pixel depth for rotation");
> +             }

Could be just 32/cpp.

> +             min_alloc = DIV_ROUND_UP((4 * p->horiz_pixels/(y_plane ? 1 : 2) 
> *
> +                     bytes_per_pixel), 512) * min_scanlines/4 + 3;

Another case that could be simplified by removing the y_plane special
casing. In fact just passing in the format and plane index in we could get:

cpp = drm_format_plane_cpp(format, plane);
width = width / drm_format_horiz_subsampling(format);
min_scanlines = 32 / cpp;
min_alloc = DIV_ROUND_UP(4 * width * cpp, 512) * min_scanlines / 4 + 3;


We could even move the width/subsampling (and height too) thing into a
common helper in a drm header, eg.:

static inline int drm_format_plane_width(format, plane, width)
{
        if (plane)
                return width / drm_format_plane_horiz_subsampling(format);
        else
                return width;
}
static inline int drm_format_plane_height(format, plane, height);
{
        if (plane)
                return height / drm_format_plane_vert_subsampling(format);
        else
                return height;
}

> +     } else {
> +             min_alloc = 8;
> +     }
> +
> +     return min_alloc;
> +}
> +
>  static void
>  skl_allocate_pipe_ddb(struct drm_crtc *crtc,
>                     const struct intel_wm_config *config,
> @@ -2999,9 +3034,9 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
>               if (!p->enabled)
>                       continue;
>  
> -             minimum[plane] = 8;
> +             minimum[plane] = skl_dbuf_min_alloc(p, 0);    /* 
> uv-plane/packed */
>               alloc_size -= minimum[plane];
> -             y_minimum[plane] = p->y_bytes_per_pixel ? 8 : 0;
> +             y_minimum[plane] = skl_dbuf_min_alloc(p, 1);  /* y-plane */

false/true instead of 0/1.

With the bool things changed this does what it says so:
Reviewed-by: Ville Syrjälä <ville.syrj...@linux.intel.com>

>               alloc_size -= y_minimum[plane];
>       }
>  
> -- 
> 1.7.9.5
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC
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