tests/kms_writeback.c: fix the `fill_fb` function

Currently, the `fill_fb` function, instead of filling the framebuffer
with the whole pixel, is only filling it with the rightmost byte.

This is happening because, even though the memset accepts an int as
a parameter, it's casting the value to unsigned char and will fill
the memory with this 8 bits value.

If we setup the pixel to 0xff0000|f0|, the buffer will filled with:

| addr     | = 0f
| addr + 1 | = 0f
| addr + 2 | = 0f
| addr + 3 | = 0f
    ...
| addr + N | = 0f

This patch address this issue by manually copying the entire integer.

Signed-off-by: Igor Torrente <igormtorrente@gmail.com>
Reviewed-by: Petri Latvala <petri.latvala@intel.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/tests/kms_writeback.c b/tests/kms_writeback.c
index 60dbda2a..a033b44f 100644
--- a/tests/kms_writeback.c
+++ b/tests/kms_writeback.c
@@ -227,14 +227,17 @@ static void writeback_fb_id(igt_output_t *output, igt_fb_t *valid_fb, igt_fb_t *
 
 static void fill_fb(igt_fb_t *fb, uint32_t pixel)
 {
-	void *ptr;
+	uint32_t *ptr;
+	int64_t pixel_count, i;
 
 	igt_assert(fb->drm_format == DRM_FORMAT_XRGB8888);
 
 	ptr = igt_fb_map_buffer(fb->fd, fb);
 	igt_assert(ptr);
 
-	memset(ptr, pixel, fb->strides[0] * fb->height);
+	pixel_count = fb->strides[0] * fb->height / sizeof(uint32_t);
+	for (i = 0; i < pixel_count; i++)
+		ptr[i] = pixel;
 
 	igt_fb_unmap_buffer(fb, ptr);
 }