Re: [PATCH 07/12] drm/i915: Limit fb x offset due to fences

[Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>]

Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>

On Tuesday 03 May 2016 09:09 PM, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> If there's a fence on the object it will be aligned to the start
> of the object, and hence CPU rendering to any fb that straddles
> the fence edge will come out wrong due to lines wrapping at the
> wrong place.
>
> We have no API to manage fences on a sub-object level, so we can't
> really fix this in any way. Additonally gen2/3 fences are rather
> coarse grained so adjusting the offset migth not even be possible.
>
> Avoid these problems by requiring the fb layout to agree with the
> fence layout (if present).
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/intel_display.c | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 68612a5fac3d..438f3bd86e48 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -2504,6 +2504,22 @@ intel_fill_fb_info(struct drm_i915_private *dev_priv,
>   		intel_fb_offset_to_xy(&x, &y, fb, i);
>   
>   		/*
> +		 * The fence (if used) is aligned to the start of the object
> +		 * so having the framebuffer wrap around across the edge of the
> +		 * fenced region doesn't really work. We have no API to configure
> +		 * the fence start offset within the object (nor could we probably
> +		 * on gen2/3). So it's just easier if we just require that the
> +		 * fb layout agrees with the fence layout. We already check that the
> +		 * fb stride matches the fence stride elsewhere.
> +		 */
> +		if (intel_fb->obj->tiling_mode != I915_TILING_NONE &&
> +		    (x + width) * cpp > fb->pitches[i]) {
> +			DRM_DEBUG("bad fb plane %d offset: 0x%x\n",
> +				  i, fb->offsets[i]);
> +			return -EINVAL;
> +		}
> +
> +		/*
>   		 * First pixel of the framebuffer from
>   		 * the start of the normal gtt mapping.
>   		 */

-- 
regards,
Sivakumar Thulasimani

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