[Intel-gfx] [PATCH 1/3] drm/i915; Protect intel_gen4_compute_offset_xtiled() against unknown pixel format

[Chris Wilson]

If the pixel format is not known to the core helpers, it fills in the
fb->bits_per_pixel field as 0. This causes a fatal divide-by-zero OOPS
when we then try to calculate the tiled offset. This would not be a
problem, but that the core helpers do not know about the YUV planar
formats we use for sprites.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_display.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 8986172..de09f47 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2019,6 +2019,9 @@ unsigned long intel_gen4_compute_offset_xtiled(int *x, int *y,
 {
 	int tile_rows, tiles;
 
+	if (bpp == 0) /* XXX unknown pixel format! */
+		return 0;
+
 	tile_rows = *y / 8;
 	*y %= 8;
 	tiles = *x / (512/bpp);
-- 
1.7.10.4