[igt-dev] [PATCH i-g-t v3 05/21] lib/igt_fb: Allow interpreting the tile height as a stride equivalent

[Lyude Paul]

Reviewed-by: Lyude Paul <lyude at redhat.com>

On Fri, 2019-01-11 at 10:05 +0100, Paul Kocialkowski wrote:
> The VC4 SAND tiling modes are disposed in columns that follow each
> other in memory. The column height defines the number of fixed-width
> lines from the beginning of one column to the other, which may be
> greater than the display height. In this case, the extra lines are
> used as padding and the column height becomes a height-based stride
> equivalent.
> 
> Support this when calculating the plane size by using the tile height
> directly if it is greater than the plane height. This works better than
> alignment for non-power-of-two cases (no space is wasted) and it is
> equivalent to alignment for power-of-two tile heights.
> 
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski at bootlin.com>
> ---
>  lib/igt_fb.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/lib/igt_fb.c b/lib/igt_fb.c
> index 7fb8e7d44bd2..03a6b8be9618 100644
> --- a/lib/igt_fb.c
> +++ b/lib/igt_fb.c
> @@ -450,6 +450,13 @@ static uint64_t calc_plane_size(struct igt_fb *fb, int
> plane)
>  		igt_get_fb_tile_size(fb->fd, fb->tiling, fb->plane_bpp[plane],
>  				     &tile_width, &tile_height);
>  
> +		/* Special case where the "tile height" represents a
> +		 * height-based stride, such as with VC4 SAND tiling modes.
> +		 */
> +
> +		if (tile_height > fb->plane_height[plane])
> +			return fb->strides[plane] * tile_height;
> +
>  		return (uint64_t) fb->strides[plane] *
>  			ALIGN(fb->plane_height[plane], tile_height);
>  	}
-- 
Cheers,
	Lyude Paul