From 85f4c1005150683397fd2775885067ce3515fe06 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 8 Mar 2022 14:23:39 +0100 Subject: lib/igt_fb: Ignore the X component when computing CRC The igt_fb_get_fnv1a_crc() function will compute a FNV-1a hash over the content of the framebuffer. The sole user of this function is the writeback test suite, which will use it to compare an XRGB8888 buffer used in input to an XRGB8888 buffer filled by the writeback connector. However, that function uses each bytes of each buffers to compute the hash, and therefore the writeback code assumes that the hardware will preserve the content of the X component through the writeback pipeline, which isn't true for all hardware. VC4 doesn't for example. Since that function is only ever used for XRGB8888 buffers, let's just set the most significant to 0 (which is the X padding) for each pixel when computing the hash, and thus ignore whatever the hardware will return here. Acked-by: Pekka Paalanen Signed-off-by: Maxime Ripard --- lib/igt_fb.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/lib/igt_fb.c b/lib/igt_fb.c index 1b9131f2..780283a0 100644 --- a/lib/igt_fb.c +++ b/lib/igt_fb.c @@ -4437,15 +4437,19 @@ int igt_fb_get_fnv1a_crc(struct igt_fb *fb, igt_crc_t *crc) { const uint32_t FNV1a_OFFSET_BIAS = 2166136261; const uint32_t FNV1a_PRIME = 16777619; + uint32_t *line = NULL; uint32_t hash; void *map; - char *ptr, *line = NULL; + char *ptr; int x, y, cpp = igt_drm_format_to_bpp(fb->drm_format) / 8; uint32_t stride = calc_plane_stride(fb, 0); if (fb->num_planes != 1) return -EINVAL; + if (fb->drm_format != DRM_FORMAT_XRGB8888) + return -EINVAL; + ptr = igt_fb_map_buffer(fb->fd, fb); igt_assert(ptr); map = ptr; @@ -4467,9 +4471,17 @@ int igt_fb_get_fnv1a_crc(struct igt_fb *fb, igt_crc_t *crc) igt_memcpy_from_wc(line, ptr, fb->width * cpp); - for (x = 0; x < fb->width * cpp; x++) { - hash ^= line[x]; - hash *= FNV1a_PRIME; + for (x = 0; x < fb->width; x++) { + unsigned int i; + uint32_t pixel = le32_to_cpu(line[x]); + pixel &= 0x00ffffff; + + for (i = 0; i < sizeof(pixel); i++) { + uint8_t component = (pixel >> (i * 8)) & 0xff; + + hash ^= component; + hash *= FNV1a_PRIME; + } } } -- cgit v1.2.3