Re: [igt-dev] [PATCH i-g-t v2 8/8] tests/kms_writeback: Use a garbage X value to create fill our test buffer

[Pekka Paalanen <ppaalanen@gmail.com>]

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On Mon, 28 Mar 2022 16:55:09 +0200
Maxime Ripard <maxime@cerno.tech> wrote:

> Since we use buffers in XRGB8888, whatever value we have in X should be
> ignored by the drivers and the hardware. However, since we always use
> 0xff in our test, whether that is the case or not cannot be determined.
> 
> Let's use a garbage value (but consistent across test runs) to make sure
> it doesn't have any impact on the writeback output.
> 
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>

Yup, this is definitely a good idea.

I proposed to do the same in VKMS when writing out to XRGB writeback
buffer after blending, but Igor had the same problem as you with IGT. I
hope this series solves it.


Thanks,
pq

> ---
>  tests/kms_writeback.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tests/kms_writeback.c b/tests/kms_writeback.c
> index 2366692865b7..4efd99713479 100644
> --- a/tests/kms_writeback.c
> +++ b/tests/kms_writeback.c
> @@ -293,7 +293,7 @@ static void writeback_sequence(igt_output_t *output, igt_plane_t *plane,
>  				igt_fb_t *in_fb, igt_fb_t *out_fbs[], int n_commits)
>  {
>  	int i = 0;
> -	uint32_t in_fb_colors[2] = { 0xffff0000, 0xff00ff00 };
> +	uint32_t in_fb_colors[2] = { 0x42ff0000, 0x4200ff00 };
>  	uint32_t clear_color = 0xffffffff;
>  
>  	igt_crc_t cleared_crc, out_expected;


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