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

[Paul Kocialkowski]

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);
 	}
-- 
2.20.1