[PATCH i-g-t] tests/kms_writeback: Check CRC capture survives writeback

[PATCH i-g-t] tests/kms_writeback: Check CRC capture survives writeback

[atipre]

The existing writeback tests validate captured framebuffer contents, but
do not keep pipe CRC capture active across writeback completion. This
misses the VKMS bug where writeback cleanup disables the composer while
CRC capture still needs it, leaving subsequent CRC reads waiting for
samples that never arrive.

Add writeback-preserves-crc. Complete the initial modeset before starting
capture and establish reference CRCs for separate red and blue input
framebuffers. Keep capture open across four alternating writebacks, wait
for each output fence, and compare three fresh CRC samples with the
corresponding reference after each writeback. Use atomic updates without
ALLOW_MODESET once capture starts, and release capture from the final
fixture so a failed subtest also closes it.

Check output fence status in the shared wait helper so a signalled error
fence cannot be treated as a successful writeback.

On ARM64 QEMU with one and two CPUs, the new subtest fails on unmodified
mainline and passes with the local VKMS composer-user lifetime
fix. Four existing applicable writeback subtests pass on both kernels;
the two XRGB2101010 subtests skip because the format probe rejects them.

Signed-off-by: atipre <tipreaditya@gmail.com>
---
 tests/kms_writeback.c | 62 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/tests/kms_writeback.c b/tests/kms_writeback.c
index 7c30e8e..71317cf 100644
--- a/tests/kms_writeback.c
+++ b/tests/kms_writeback.c
@@ -64,6 +64,10 @@
  *
  * SUBTEST: writeback-pixel-formats
  * Description: Check the writeback format
+ *
+ * SUBTEST: writeback-preserves-crc
+ * Description: CRC capture remains active across completed writebacks
+ * Driver requirement: i915, xe, vkms
  */
 
 IGT_TEST_DESCRIPTION(
@@ -317,6 +321,7 @@ static void get_and_wait_out_fence(igt_output_t *output)
 
 	ret = sync_fence_wait(output->writeback_out_fence_fd, 1000);
 	igt_assert_f(ret == 0, "sync_fence_wait failed: %s\n", strerror(-ret));
+	igt_assert_eq(sync_fence_status(output->writeback_out_fence_fd), 1);
 	close(output->writeback_out_fence_fd);
 	output->writeback_out_fence_fd = -1;
 }
@@ -537,6 +542,7 @@ int igt_main_args("b:c:f:dl", long_options, help_str, opt_handler, NULL)
 	igt_output_t *output;
 	igt_plane_t *plane;
 	igt_fb_t input_fb, input_fb_10bit;
+	static igt_pipe_crc_t *pipe_crc;
 	drmModeModeInfo mode;
 	unsigned int fb_id;
 	int ret;
@@ -709,7 +715,63 @@ int igt_main_args("b:c:f:dl", long_options, help_str, opt_handler, NULL)
 		igt_remove_fb(display.drm_fd, &output_fb);
 	}
 
+	igt_describe("CRC capture remains active across completed writebacks");
+	igt_subtest("writeback-preserves-crc") {
+		igt_fb_t blue_fb, output_fb;
+		igt_fb_t *colors[] = { &input_fb, &blue_fb };
+		igt_crc_t reference[2], crc;
+		int i, j;
+
+		igt_skip_on(data.dump_check || data.list_modes);
+		igt_require(data.supported_colors & XRGB8888);
+		igt_require_pipe_crc(display.drm_fd);
+
+		igt_create_color_fb(display.drm_fd, mode.hdisplay, mode.vdisplay,
+				    DRM_FORMAT_XRGB8888, DRM_FORMAT_MOD_LINEAR,
+				    0.0, 0.0, 1.0, &blue_fb);
+		igt_create_fb(display.drm_fd, mode.hdisplay, mode.vdisplay,
+			      DRM_FORMAT_XRGB8888, DRM_FORMAT_MOD_LINEAR,
+			      &output_fb);
+		fill_fb(&input_fb, 0x00ff0000);
+		igt_plane_set_fb(plane, &input_fb);
+		igt_output_set_writeback_fb(output, NULL);
+		igt_display_commit_atomic(&display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
+
+		/* Finish the modeset before starting continuous CRC capture. */
+		pipe_crc = igt_pipe_crc_new(display.drm_fd, output->config.crtc_index,
+					    IGT_PIPE_CRC_SOURCE_AUTO);
+		igt_pipe_crc_start(pipe_crc);
+
+		/* Establish both references before writeback can affect capture. */
+		for (i = 0; i < ARRAY_SIZE(colors); i++) {
+			igt_plane_set_fb(plane, colors[i]);
+			igt_display_commit_atomic(&display, 0, NULL);
+			igt_pipe_crc_get_current(display.drm_fd, pipe_crc, &reference[i]);
+		}
+
+		for (i = 0; i < 4; i++) {
+			int color = i % ARRAY_SIZE(colors);
+
+			igt_plane_set_fb(plane, colors[color]);
+			igt_output_set_writeback_fb(output, &output_fb);
+			igt_display_commit_atomic(&display, 0, NULL);
+			get_and_wait_out_fence(output);
+
+			/* Require fresh frames without stopping or restarting capture. */
+			for (j = 0; j < 3; j++) {
+				igt_pipe_crc_get_current(display.drm_fd, pipe_crc, &crc);
+				igt_assert_crc_equal(&reference[color], &crc);
+			}
+		}
+
+		igt_plane_set_fb(plane, &input_fb);
+		igt_display_commit_atomic(&display, 0, NULL);
+		igt_remove_fb(display.drm_fd, &blue_fb);
+		igt_remove_fb(display.drm_fd, &output_fb);
+	}
+
 	igt_fixture() {
+		igt_pipe_crc_free(pipe_crc);
 		cleanup_writeback(&display, output);
 		igt_remove_fb(display.drm_fd, &input_fb);
 

base-commit: bb76404eac7032ba85c53eac15b76e4fadaff0de
-- 
2.50.1 (Apple Git-155)

Re: [PATCH i-g-t] tests/kms_writeback: Check CRC capture survives writeback

[Kamil Konieczny]

Hi atipre,
On 2026-10-25 at 14:24:20 -0400, atipre wrote:
> The existing writeback tests validate captured framebuffer contents, but
> do not keep pipe CRC capture active across writeback completion. This
> misses the VKMS bug where writeback cleanup disables the composer while
> CRC capture still needs it, leaving subsequent CRC reads waiting for
> samples that never arrive.
> 
> Add writeback-preserves-crc. Complete the initial modeset before starting
> capture and establish reference CRCs for separate red and blue input
> framebuffers. Keep capture open across four alternating writebacks, wait
> for each output fence, and compare three fresh CRC samples with the
> corresponding reference after each writeback. Use atomic updates without
> ALLOW_MODESET once capture starts, and release capture from the final
> fixture so a failed subtest also closes it.
> 
> Check output fence status in the shared wait helper so a signalled error
> fence cannot be treated as a successful writeback.
> 
> On ARM64 QEMU with one and two CPUs, the new subtest fails on unmodified
> mainline and passes with the local VKMS composer-user lifetime
> fix. Four existing applicable writeback subtests pass on both kernels;
> the two XRGB2101010 subtests skip because the format probe rejects them.
> 
> Signed-off-by: atipre <tipreaditya@gmail.com>

It would be preferable to have Full Name instead of nick,
should this be:
Signed-off-by: Tipre Aditya <tipreaditya@gmail.com>
?


If yes, add also same From: at beginnig or configure your git.

+cc Swati and Karthik
Cc: Karthik B S <karthik.b.s@intel.com>
Cc: Swati Sharma <swati2.sharma@intel.com>

Regards,
Kamil

> ---
>  tests/kms_writeback.c | 62 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
> 
> diff --git a/tests/kms_writeback.c b/tests/kms_writeback.c
> index 7c30e8e..71317cf 100644
> --- a/tests/kms_writeback.c
> +++ b/tests/kms_writeback.c
> @@ -64,6 +64,10 @@
>   *
>   * SUBTEST: writeback-pixel-formats
>   * Description: Check the writeback format
> + *
> + * SUBTEST: writeback-preserves-crc
> + * Description: CRC capture remains active across completed writebacks
> + * Driver requirement: i915, xe, vkms
>   */
>  
>  IGT_TEST_DESCRIPTION(
> @@ -317,6 +321,7 @@ static void get_and_wait_out_fence(igt_output_t *output)
>  
>  	ret = sync_fence_wait(output->writeback_out_fence_fd, 1000);
>  	igt_assert_f(ret == 0, "sync_fence_wait failed: %s\n", strerror(-ret));
> +	igt_assert_eq(sync_fence_status(output->writeback_out_fence_fd), 1);
>  	close(output->writeback_out_fence_fd);
>  	output->writeback_out_fence_fd = -1;
>  }
> @@ -537,6 +542,7 @@ int igt_main_args("b:c:f:dl", long_options, help_str, opt_handler, NULL)
>  	igt_output_t *output;
>  	igt_plane_t *plane;
>  	igt_fb_t input_fb, input_fb_10bit;
> +	static igt_pipe_crc_t *pipe_crc;
>  	drmModeModeInfo mode;
>  	unsigned int fb_id;
>  	int ret;
> @@ -709,7 +715,63 @@ int igt_main_args("b:c:f:dl", long_options, help_str, opt_handler, NULL)
>  		igt_remove_fb(display.drm_fd, &output_fb);
>  	}
>  
> +	igt_describe("CRC capture remains active across completed writebacks");
> +	igt_subtest("writeback-preserves-crc") {
> +		igt_fb_t blue_fb, output_fb;
> +		igt_fb_t *colors[] = { &input_fb, &blue_fb };
> +		igt_crc_t reference[2], crc;
> +		int i, j;
> +
> +		igt_skip_on(data.dump_check || data.list_modes);
> +		igt_require(data.supported_colors & XRGB8888);
> +		igt_require_pipe_crc(display.drm_fd);
> +
> +		igt_create_color_fb(display.drm_fd, mode.hdisplay, mode.vdisplay,
> +				    DRM_FORMAT_XRGB8888, DRM_FORMAT_MOD_LINEAR,
> +				    0.0, 0.0, 1.0, &blue_fb);
> +		igt_create_fb(display.drm_fd, mode.hdisplay, mode.vdisplay,
> +			      DRM_FORMAT_XRGB8888, DRM_FORMAT_MOD_LINEAR,
> +			      &output_fb);
> +		fill_fb(&input_fb, 0x00ff0000);
> +		igt_plane_set_fb(plane, &input_fb);
> +		igt_output_set_writeback_fb(output, NULL);
> +		igt_display_commit_atomic(&display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
> +
> +		/* Finish the modeset before starting continuous CRC capture. */
> +		pipe_crc = igt_pipe_crc_new(display.drm_fd, output->config.crtc_index,
> +					    IGT_PIPE_CRC_SOURCE_AUTO);
> +		igt_pipe_crc_start(pipe_crc);
> +
> +		/* Establish both references before writeback can affect capture. */
> +		for (i = 0; i < ARRAY_SIZE(colors); i++) {
> +			igt_plane_set_fb(plane, colors[i]);
> +			igt_display_commit_atomic(&display, 0, NULL);
> +			igt_pipe_crc_get_current(display.drm_fd, pipe_crc, &reference[i]);
> +		}
> +
> +		for (i = 0; i < 4; i++) {
> +			int color = i % ARRAY_SIZE(colors);
> +
> +			igt_plane_set_fb(plane, colors[color]);
> +			igt_output_set_writeback_fb(output, &output_fb);
> +			igt_display_commit_atomic(&display, 0, NULL);
> +			get_and_wait_out_fence(output);
> +
> +			/* Require fresh frames without stopping or restarting capture. */
> +			for (j = 0; j < 3; j++) {
> +				igt_pipe_crc_get_current(display.drm_fd, pipe_crc, &crc);
> +				igt_assert_crc_equal(&reference[color], &crc);
> +			}
> +		}
> +
> +		igt_plane_set_fb(plane, &input_fb);
> +		igt_display_commit_atomic(&display, 0, NULL);
> +		igt_remove_fb(display.drm_fd, &blue_fb);
> +		igt_remove_fb(display.drm_fd, &output_fb);
> +	}
> +
>  	igt_fixture() {
> +		igt_pipe_crc_free(pipe_crc);
>  		cleanup_writeback(&display, output);
>  		igt_remove_fb(display.drm_fd, &input_fb);
>  
> 
> base-commit: bb76404eac7032ba85c53eac15b76e4fadaff0de
> -- 
> 2.50.1 (Apple Git-155)
> 

✗ LGCI.VerificationFailed: failure for tests/kms_writeback: Check CRC capture survives writeback

[Patchwork]

== Series Details ==

Series: tests/kms_writeback: Check CRC capture survives writeback
URL   : https://patchwork.freedesktop.org/series/176841/
State : failure

== Summary ==

Series author address 'tipreaditya@gmail.com' is not on the allowlist, which prevents CI from being automatically triggered.
If you want CI to run for this series, ask Patchwork project owners to click 'retest' on the series in Patchwork.
Exception occurred during validation, bailing out!
Build URL: http://gfx-ci.igk.intel.com:8080/job/CI_IGTPW_check/243181/ (on cidrm1)