[igt-dev] [PATCH 4/4] [RFC] tests/kms_big_fb: Wait for vblank before collecting CRC

[Juha-Pekka Heikkila]

On 27.5.2021 17.31, Vidya Srinivas wrote:
> Without wait for vblank, CRC mismatch is seen
> between big and small CRC on some intel Gen11 platforms.
> 
> Change-Id: I3bec931aa901130997e693ac1cacf389e2a8100f
> Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
> ---
>   tests/kms_big_fb.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/tests/kms_big_fb.c b/tests/kms_big_fb.c
> index b2027b6b9d1b..da682593429b 100644
> --- a/tests/kms_big_fb.c
> +++ b/tests/kms_big_fb.c
> @@ -254,6 +254,7 @@ static void unset_lut(data_t *data)
>   static bool test_plane(data_t *data)
>   {
>   	igt_plane_t *plane = data->plane;
> +	igt_display_t *display = &data->display;
>   	struct igt_fb *small_fb = &data->small_fb;
>   	struct igt_fb *big_fb = &data->big_fb;
>   	int w = data->big_fb_width - small_fb->width;
> @@ -269,6 +270,7 @@ static bool test_plane(data_t *data)
>   		{ w / 3, h * 3 / 4, },
>   		{ w, h, },
>   	};
> +	bool check_platform_intel = is_i915_device(data->drm_fd);

You will not need to do this. This test start with

drm_open_driver_master(DRIVER_INTEL)

hence will always be only on intel device.

>   
>   	if (!igt_plane_has_format_mod(plane, data->format, data->modifier))
>   		return false;
> @@ -336,17 +338,19 @@ static bool test_plane(data_t *data)
>   
>   		igt_display_commit2(&data->display, data->display.is_atomic ?
>   				    COMMIT_ATOMIC : COMMIT_UNIVERSAL);
> -
> -
> +		if (check_platform_intel)
> +			igt_wait_for_vblank(data->drm_fd, display->pipes[data->pipe].crtc_offset);

Above this line there's flip to different framebuffer and below this 
line there's restart of crc collection before get any crc. If there's 
need to wait a vblank at this place to get matching crcs the actual bug 
is somewhere else.

>   		igt_pipe_crc_collect_crc(data->pipe_crc, &small_crc);
>   
>   		igt_plane_set_fb(plane, big_fb);
>   		igt_fb_set_position(big_fb, plane, x, y);
>   		igt_fb_set_size(big_fb, plane, small_fb->width, small_fb->height);
> +
>   		igt_plane_set_size(plane, data->width, data->height);
>   		igt_display_commit2(&data->display, data->display.is_atomic ?
>   				    COMMIT_ATOMIC : COMMIT_UNIVERSAL);
> -
> +		if (check_platform_intel)
> +			igt_wait_for_vblank(data->drm_fd, display->pipes[data->pipe].crtc_offset);

Here it's the same story as above.

>   		igt_pipe_crc_collect_crc(data->pipe_crc, &big_crc);
>   
>   		igt_plane_set_fb(plane, NULL);
>