Re: [PATCH i-g-t 5/7] tests/intel/kms_dp_linktrain_fallback: add dsc-fallback test

["Sharma, Swati2" <swati2.sharma@intel.com>]

Hi Kunal,

On 11-02-2025 11:35 pm, Kunal Joshi wrote:
> Add new dsc-fallback test to check whether DSC
> automatically kicks in while falling back to a
> lower rate/lane.
>
> v2: fix description (Swati)
>      fix indentation (Swati)
>      remove extra line (Swati)
>      make commit description clear (Ankit)
>      split refactor and dsc-fallback test (Ankit)
>      switch to igt_debug (Ankit)
>
> v3: use macro instead of magic number (Ankit)
>      fix test order (Ankit)
>      new line before return (Ankit)
>
> Signed-off-by: Kunal Joshi <kunal1.joshi@intel.com>
> Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>   tests/intel/kms_dp_linktrain_fallback.c | 162 +++++++++++++++++++++++-
>   tests/meson.build                       |   4 +-
>   2 files changed, 162 insertions(+), 4 deletions(-)
>
> diff --git a/tests/intel/kms_dp_linktrain_fallback.c b/tests/intel/kms_dp_linktrain_fallback.c
> index c6e9fba53..d26e25bba 100644
> --- a/tests/intel/kms_dp_linktrain_fallback.c
> +++ b/tests/intel/kms_dp_linktrain_fallback.c
> @@ -17,10 +17,14 @@
>   #include "igt_sysfs.h"
>   #include "igt.h"
>   #include "kms_mst_helper.h"
> +#include "kms_dsc_helper.h"
>   
>   /**
>    * SUBTEST: dp-fallback
>    * Description: Test fallback on DP connectors
> + *
> + * SUBTEST: dsc-fallback
> + * Description: Test fallback to DSC when BW isn't sufficient
Please add functionality here as dsc.
>    */
>   
>   #define RETRAIN_COUNT 1
> @@ -46,7 +50,7 @@ typedef struct {
>   
>   typedef int (*condition_check_fn)(int drm_fd, igt_output_t *output);
>   
> -IGT_TEST_DESCRIPTION("Test link training fallback");
> +IGT_TEST_DESCRIPTION("Test link-training / dsc fallback");
>   
>   static bool setup_mst_outputs(data_t *data, igt_output_t *mst_output[],
>   			      int *output_count)
> @@ -424,7 +428,7 @@ static void test_fallback(data_t *data, bool is_mst)
>   	}
>   }
>   
> -static bool run_test(data_t *data)
> +static bool run_lt_fallback_test(data_t *data)
>   {
>   	bool ran = false;
>   	igt_output_t *output;
> @@ -462,6 +466,153 @@ static bool run_test(data_t *data)
>   	return ran;
>   }
>   
> +static void test_dsc_sst_fallback(data_t *data)
> +{
> +	bool non_dsc_mode_found = false;
> +	bool dsc_fallback_successful = false;
> +	int ret;
> +	struct udev_monitor *mon;
> +	drmModeModeInfo *mode_to_check;
> +	igt_output_t *outputs[IGT_MAX_PIPES];
> +	int output_count = 0;
> +
> +	igt_info("Checking DSC fallback on %s\n", igt_output_name(data->output));
> +	data->pipe = PIPE_A;
> +
> +	igt_display_reset(&data->display);
> +	igt_reset_link_params(data->drm_fd, data->output);
> +	igt_force_link_retrain(data->drm_fd, data->output, RETRAIN_COUNT);
> +
> +	/* Find a mode that doesn't require DSC initially */
> +	for_each_connector_mode(data->output) {
> +		data->mode = &data->output->config.connector->modes[j__];
> +		igt_create_color_fb(data->drm_fd, data->mode->hdisplay,
> +				    data->mode->vdisplay, DRM_FORMAT_XRGB8888,
> +				    DRM_FORMAT_MOD_LINEAR, 0.0, 1.0, 0.0,
> +				    &data->fb);
> +		igt_output_override_mode(data->output, data->mode);
> +		igt_output_set_pipe(data->output, data->pipe);
> +		data->primary = igt_output_get_plane_type(data->output,
> +						DRM_PLANE_TYPE_PRIMARY);
> +		igt_plane_set_fb(data->primary, &data->fb);
> +
> +		ret = igt_display_try_commit_atomic(&data->display,
> +						    DRM_MODE_ATOMIC_TEST_ONLY |
> +						    DRM_MODE_ATOMIC_ALLOW_MODESET,
> +						    NULL);
> +		if (ret != 0) {
> +			igt_debug("Skipping mode %dx%d@%d on %s\n",
> +				 data->mode->hdisplay, data->mode->vdisplay,
> +				 data->mode->vrefresh,
> +				 igt_output_name(data->output));
> +			continue;
> +		}
> +		igt_display_commit2(&data->display, COMMIT_ATOMIC);
> +
> +		if (!igt_is_dsc_enabled(data->drm_fd,
> +					data->output->name)) {
> +			drmModeModeInfo *non_dsc_mode
> +				= igt_output_get_mode(data->output);
> +			igt_info("Found mode %dx%d@%d %s that doesn't need DSC with link rate %d and lane count %d\n",
> +				 non_dsc_mode->hdisplay, non_dsc_mode->vdisplay,
> +				 non_dsc_mode->vrefresh, non_dsc_mode->name,
> +				 igt_get_current_link_rate(data->drm_fd, data->output),
> +				 igt_get_current_lane_count(data->drm_fd, data->output));
> +			non_dsc_mode_found = true;
> +			break;
> +		}
> +	}
> +	igt_require_f(non_dsc_mode_found,
> +		      "No non-DSC mode found on %s\n",
> +		      igt_output_name(data->output));
> +
> +	/* Repeatedly force link failure until DSC is required (or link is disabled) */
> +	while (!igt_get_dp_link_retrain_disabled(data->drm_fd, data->output)) {
> +		mon = igt_watch_uevents();
> +
> +		igt_assert_f(force_failure_and_wait(data, data->output,
> +						    LT_FAILURE_REDUCED_CAPS,
> +						    RETRAIN_COUNT, 1.0, 20.0),
> +			     "Forcing DSC fallback timed out\n");
> +
> +		if (igt_get_dp_link_retrain_disabled(data->drm_fd,
> +						     data->output)) {
> +			igt_reset_connectors();
> +			igt_flush_uevents(mon);
> +			return;
> +		}
> +
> +		igt_assert_f(wait_for_hotplug_and_check_bad(data->drm_fd,
> +							    data,
> +							    data->output,
> +							    mon,
> +							    20.0),
> +			     "Didn't get hotplug or link-status=BAD for DSC\n");
> +		igt_flush_uevents(mon);
> +
> +		outputs[output_count++] = data->output;
> +		set_connector_link_status_good(data, outputs, &output_count);
> +		igt_display_commit2(&data->display, COMMIT_ATOMIC);
> +
> +		mode_to_check = igt_output_get_mode(data->output);
> +
> +		if (igt_is_dsc_enabled(data->drm_fd, data->output->name)) {
> +			igt_info("mode %dx%d@%d now requires DSC with link rate %d and lane count %d\n",
> +				 mode_to_check->hdisplay, mode_to_check->vdisplay,
> +				 mode_to_check->vrefresh,
> +				 igt_get_current_link_rate(data->drm_fd, data->output),
> +				 igt_get_current_lane_count(data->drm_fd, data->output));
> +			igt_info("DSC fallback successful on %s\n",
> +				 igt_output_name(data->output));
> +			dsc_fallback_successful = true;
> +			break;
> +		} else {
> +			igt_info("mode %dx%d@%d still doesn't require DSC\n",
> +				 mode_to_check->hdisplay, mode_to_check->vdisplay,
> +				 mode_to_check->vrefresh);
> +		}
> +	}
> +	igt_assert_f(dsc_fallback_successful, "DSC fallback unsuccessful\n");
> +}
> +
> +static bool run_dsc_sst_fallaback_test(data_t *data)
> +{
> +	bool ran = false;
> +	igt_output_t *output;
> +
> +	if (!is_dsc_supported_by_source(data->drm_fd)) {
> +		igt_info("DSC not supported by source.\n");
> +		return ran;
> +	}
> +
> +	for_each_connected_output(&data->display, output) {
> +		data->output = output;
> +
> +		if (!igt_has_force_link_training_failure_debugfs(data->drm_fd,
> +								 data->output)) {
> +			igt_info("Output %s doesn't support forcing link training.\n",
> +				 igt_output_name(data->output));
> +			continue;
> +		}
> +
> +		if (output->config.connector->connector_type != DRM_MODE_CONNECTOR_DisplayPort) {
> +			igt_info("Skipping output %s as it's not DP\n", output->name);
> +			continue;
> +		}
> +
> +		if (!is_dsc_supported_by_sink(data->drm_fd, data->output)) {
> +			igt_info("Skipping output %s as DSC not supported by sink\n",
> +				 igt_output_name(data->output));
> +			continue;
> +		}
> +
> +		ran = true;
> +		test_dsc_sst_fallback(data);
> +	}
> +
> +	return ran;
> +}
> +
>   igt_main
>   {
>   	data_t data = {};
> @@ -486,10 +637,15 @@ igt_main
>   	}
>   
>   	igt_subtest("dp-fallback") {
> -		igt_require_f(run_test(&data),
> +		igt_require_f(run_lt_fallback_test(&data),
>   			      "Skipping test as no output found or none supports fallback\n");
>   	}
>   
> +	igt_subtest("dsc-fallback") {
> +		igt_require_f(run_dsc_sst_fallaback_test(&data),
> +			      "Skipping test: DSC fallback conditions not met.\n");
Make this skip statement as consistent to above. Remove : and full stop
Something like
"Skipping test as DSC fallback..."
> +	}
> +
>   	igt_fixture {
>   		igt_remove_fb(data.drm_fd, &data.fb);
>   		igt_display_fini(&data.display);
> diff --git a/tests/meson.build b/tests/meson.build
> index a6f6ad560..95892762e 100644
> --- a/tests/meson.build
> +++ b/tests/meson.build
> @@ -366,7 +366,9 @@ extra_sources = {
>   	'kms_chamelium_edid': [ join_paths ('chamelium', 'kms_chamelium_helper.c') ],
>   	'kms_chamelium_frames': [ join_paths ('chamelium', 'kms_chamelium_helper.c') ],
>   	'kms_chamelium_hpd': [ join_paths ('chamelium', 'kms_chamelium_helper.c') ],
> -	'kms_dp_linktrain_fallback': [ join_paths ('intel', 'kms_mst_helper.c') ],
> +	'kms_dp_linktrain_fallback': [
> +           join_paths ('intel', 'kms_mst_helper.c'),
> +           join_paths ('intel', 'kms_dsc_helper.c') ],
>   	'kms_dsc': [ join_paths ('intel', 'kms_dsc_helper.c') ],
>   	'kms_psr2_sf':  [ join_paths ('intel', 'kms_dsc_helper.c') ],
>   }