Re: [i-g-t,v3] tests/kms_bw: Allow custom modes for external panels

["Joshi, Kunal1" <kunal1.joshi@intel.com>]

On 20-04-2026 11:42, Karthik B S wrote:
> Currently, the test is rejecting outputs where the mode does not match.
> This is leading to excessive skips on configs where the tests
> were passing previously.
>
> Instead of this, use default mode for fixed-mode panels if the required
> custom mode is not found, and use custom mode for external panels as
> these are allowed and have also been passing previously.
>
> v2: Fixes in output_supported_mode (Kunal)
>      Add description to call out fixed-mode on internal panels (Kunal)
>
> v3: Fix documentation issue on compilation.
>
> Cc: Jason-JH Lin <jason-jh.lin@mediatek.com>
> Cc: Kunal Joshi <kunal1.joshi@intel.com>
> Signed-off-by: Karthik B S <karthik.b.s@intel.com>
> Tested-by: Jason-JH Lin <jason-jh.lin@mediatek.com>
> ---
>   tests/kms_bw.c | 82 +++++++++++++++++++++++++++++++++++---------------
>   1 file changed, 58 insertions(+), 24 deletions(-)
>
> diff --git a/tests/kms_bw.c b/tests/kms_bw.c
> index 4df5c2cee..fea7d9d38 100644
> --- a/tests/kms_bw.c
> +++ b/tests/kms_bw.c
> @@ -35,7 +35,7 @@
>   #include <xf86drmMode.h>
>   
>   /**
> - * SUBTEST: linear-tiling-%d-displays-%s
> + * SUBTEST: linear-tiling-%d-displays-target-%s
>    * Description: bw test with %arg[2]
>    *
>    * arg[1].values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
> @@ -47,7 +47,7 @@
>    * @3840x2160p:       3840x2160 resolution
>    * @2160x1440p:       2160x1440 resolution
>    *
> - * SUBTEST: connected-linear-tiling-%d-displays-%s
> + * SUBTEST: connected-linear-tiling-%d-displays-target-%s
>    * Description: bw test with %arg[2]
>    *
>    * arg[1].values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
> @@ -186,14 +186,16 @@ static void force_output_mode(data_t *d, igt_output_t *output,
>   	igt_output_override_mode(output, mode);
>   }
>   
> -static bool output_mode_supported(igt_output_t *output, const drmModeModeInfo *mode)
> +/* Check if output has a matching mode and call it out if mode is being forced */
> +static void log_output_mode_support(igt_output_t *output, const drmModeModeInfo *mode)
>   {
>   	drmModeConnector *connector = output->config.connector;
> +	drmModeModeInfo *default_mode;
>   	int i;
>   
>   	/* Virtual/forced sinks support all modes */
>   	if (!igt_output_is_connected(output))
> -		return true;
> +		return;
>   
>   	for (i = 0; i < connector->count_modes; i++) {
>   		drmModeModeInfo *conn_mode = &connector->modes[i];
> @@ -204,26 +206,33 @@ static bool output_mode_supported(igt_output_t *output, const drmModeModeInfo *m
>   			igt_debug("Found matching mode for %dx%d@%dHz on %s\n",
>   				  mode->hdisplay, mode->vdisplay, mode->vrefresh,
>   				  igt_output_name(output));
> -			return true;
> +			return;
>   		}
>   	}
>   
> -	igt_info("Mode %dx%d@%dHz not supported by %s (has %d modes)\n",
> -		 mode->hdisplay, mode->vdisplay, mode->vrefresh,
> -		 igt_output_name(output), connector->count_modes);
> -
> -	return false;
> +	if (output_is_internal_panel(output)) {
> +		default_mode = igt_output_get_mode(output);
> +		igt_info("Mode %dx%d@%dHz not supported by %s (has %d modes).\n"
> +			 "%s Default mode: %dx%d@%dHz\n",
> +			 mode->hdisplay, mode->vdisplay, mode->vrefresh,
> +			 igt_output_name(output), connector->count_modes, igt_output_name(output),
> +			 default_mode->hdisplay, default_mode->vdisplay, default_mode->vrefresh);
> +	} else {
> +		igt_info("Mode %dx%d@%dHz not supported by %s (has %d modes). Forcing mode.\n",
> +			 mode->hdisplay, mode->vdisplay, mode->vrefresh,
> +			 igt_output_name(output), connector->count_modes);
> +	}
>   }
>   
>   static void run_test_linear_tiling(data_t *data, int n_crtcs, const drmModeModeInfo *mode, bool physical) {
>   	igt_display_t *display = &data->display;
>   	igt_output_t *output;
> +	drmModeModeInfo fb_mode;
>   	struct igt_fb buffer[IGT_MAX_PIPES];
>   	igt_crc_t zero, captured[IGT_MAX_PIPES];
>   	int i = 0, num_pipes = 0;
>   	igt_crtc_t *crtc;
>   	int ret;
> -	bool has_supported_mode = false;
>   
>   	/* Cannot use igt_display_n_crtcs() due to fused pipes on i915 where they do
>   	 * not give the numver of valid crtcs and always return IGT_MAX_PIPES */
> @@ -242,14 +251,28 @@ static void run_test_linear_tiling(data_t *data, int n_crtcs, const drmModeModeI
>   		crtc = data->crtc[i];
>   
>   		output = physical ? data->connected_output[i] : data->output[i];
> -		if (!output || !output_mode_supported(output, mode)) {
> +		if (!output)
>   			continue;
> -		}
>   
> -		force_output_mode(data, output, mode);
> +		log_output_mode_support(output, mode);
> +
> +		/*
> +		 * On fixed mode panels trying to force a custom mode can lead
> +		 * to failures or implicit handling where the default mode is
> +		 * used even though custom mode is requested.
> +		 *
> +		 * To avoid this use default mode on fixed mode panels and
> +		 * use custom modes only on external panels.
> +		 */
> +		if (output_is_internal_panel(output)) {
> +			fb_mode = *igt_output_get_mode(output);
> +		} else {
> +			force_output_mode(data, output, mode);
> +			fb_mode = *mode;
> +		}
>   
> -		igt_create_color_fb(display->drm_fd, mode->hdisplay,
> -				    mode->vdisplay, DRM_FORMAT_XRGB8888,
> +		igt_create_color_fb(display->drm_fd, fb_mode.hdisplay,
> +				    fb_mode.vdisplay, DRM_FORMAT_XRGB8888,
>   				    DRM_FORMAT_MOD_LINEAR, 1.f, 0.f, 0.f,
>   				    &buffer[i]);
>   
> @@ -258,10 +281,8 @@ static void run_test_linear_tiling(data_t *data, int n_crtcs, const drmModeModeI
>   		igt_plane_set_fb(data->primary[i], &buffer[i]);
>   		igt_info("Assigning pipe %s to output %s with mode %s\n",
>   			 igt_crtc_name(crtc), igt_output_name(output),
> -			 mode->name);
> -		has_supported_mode = true;
> +			 fb_mode.name);
>   	}
> -	igt_skip_on_f(!has_supported_mode, "Unsupported mode for all pipes\n");
>   
>   	ret = igt_display_try_commit_atomic(display,
>   					    DRM_MODE_ATOMIC_ALLOW_MODESET |
> @@ -273,9 +294,8 @@ static void run_test_linear_tiling(data_t *data, int n_crtcs, const drmModeModeI
>   
>   	for (i = 0; i < n_crtcs; i++) {
>   		output = physical ? data->connected_output[i] : data->output[i];
> -		if (!output || !output_mode_supported(output, mode)) {
> +		if (!output)
>   			continue;
> -		}
>   
>   		igt_pipe_crc_collect_crc(data->pipe_crc[i], &captured[i]);
>   		igt_assert_f(!igt_check_crc_equal(&zero, &captured[i]),
> @@ -284,7 +304,7 @@ static void run_test_linear_tiling(data_t *data, int n_crtcs, const drmModeModeI
>   
>   	for (i = n_crtcs - 1; i >= 0; i--) {
>   		output = physical ? data->connected_output[i] : data->output[i];
> -		if (!output || !output_mode_supported(output, mode))
> +		if (!output)
>   			continue;
>   
>   		igt_remove_fb(display->drm_fd, &buffer[i]);
> @@ -319,7 +339,14 @@ int igt_main()
>   		n_crtcs = i + 1;
>   
>   		for (j = 0; j < ARRAY_SIZE(test_mode); j++) {
> -			igt_subtest_f("linear-tiling-%d-displays-%s", n_crtcs, test_mode[j].name)
> +			igt_describe("Exercise bandwidth test using linear tiling across multiple pipes "
> +				     "on a combination of phical and/or virtual outputs."
NIT : Typo : physical
Can be fixed while merging.
> +				     "The test targets a bandwidth configuration corresponding to the "
> +				     "requested mode, forcing the mode on external or virtual outputs"
> +				     "(where supported).On fixed-mode internal panels, if the native mode "
> +				     "is used even if it does not match the requested mode.");
> +			igt_subtest_f("linear-tiling-%d-displays-target-%s",
> +				      n_crtcs, test_mode[j].name)
>   				run_test_linear_tiling(&data, n_crtcs, &test_mode[j], false);
>   		}
>   	}
> @@ -328,7 +355,14 @@ int igt_main()
>   		n_crtcs = i + 1;
>   
>                   for (j = 0; j < ARRAY_SIZE(test_mode); j++) {
> -                        igt_subtest_f("connected-linear-tiling-%d-displays-%s", n_crtcs, test_mode[j].name)
> +			igt_describe("Exercise bandwidth test using linear tiling across multiple pipes "
> +				     "on physically connected outputs only."
> +				     "The test targets a bandwidth configuration corresponding to the "
> +				     "requested mode, forcing the mode on external panels."
> +				     "On fixed-mode internal panels, if the native mode "
> +				     "is used even if it does not match the requested mode.");
NIT : Remove if, Can be fixed while merging
On fixed-mode internal panels, [if] the native mode is used even if it 
does not match the requested mode.
On fixed-mode internal panels, the native mode is used even if it does 
not match the requested mode.

LGTM
Reviewed-by: Kunal Joshi <kunal1.joshi@intel.com>
> +			igt_subtest_f("connected-linear-tiling-%d-displays-target-%s",
> +				      n_crtcs, test_mode[j].name)
>   				run_test_linear_tiling(&data, n_crtcs, &test_mode[j], true);
>                   }
>           }