[i-g-t,3/5] lib/igt_kms: add function to set link params

[Murthy, Arun R]

On 03-02-2025 13:42, Kunal Joshi wrote:
> add function to force link rate and lane count
> for given output, install exit handle to set auto
> at exit
>
> Signed-off-by: Kunal Joshi <kunal1.joshi at intel.com>
> ---

Reviewed-by: Arun R Murthy <arun.r.murthy at intel.com>

Thanks and Regards,
Arun R Murthy
-------------------

>   lib/igt_kms.c | 33 +++++++++++++++++++++++++++++++++
>   lib/igt_kms.h |  2 ++
>   2 files changed, 35 insertions(+)
>
> diff --git a/lib/igt_kms.c b/lib/igt_kms.c
> index 90f44b4d3..424056252 100644
> --- a/lib/igt_kms.c
> +++ b/lib/igt_kms.c
> @@ -7190,6 +7190,39 @@ void igt_reset_link_params(int drm_fd, igt_output_t *output)
>   	drmModeFreeConnector(temp);
>   }
>   
> +/**
> + * igt_set_link_params:
> + * @drm_fd: A drm file descriptor
> + * @output: Target output
> + *
> + * set link rate and lane count to given value, also installs exit handler
> + * to set link rate and lane count to auto on exit
> + */
> +void igt_set_link_params(int drm_fd, igt_output_t *output,
> +			   char *link_rate, char *lane_count)
> +{
> +	bool valid;
> +	drmModeConnector *temp;
> +
> +	valid = true;
> +	valid = valid && connector_attr_set_debugfs(drm_fd, output->config.connector,
> +						    "i915_dp_force_link_rate",
> +						    link_rate, "auto", true);
> +	valid = valid && connector_attr_set_debugfs(drm_fd, output->config.connector,
> +						    "i915_dp_force_lane_count",
> +						    lane_count, "auto", true);
> +	igt_assert_f(valid, "Unable to set attr or install exit handler\n");
> +	dump_connector_attrs();
> +	igt_install_exit_handler(reset_connectors_at_exit);
> +
> +	/*
> +	 * To allow callers to always use GetConnectorCurrent we need to force a
> +	 * redetection here.
> +	 */
> +	temp = drmModeGetConnector(drm_fd, output->config.connector->connector_id);
> +	drmModeFreeConnector(temp);
> +}
> +
>   /**
>    * igt_backlight_read:
>    * @result:	Pointer to store the result
> diff --git a/lib/igt_kms.h b/lib/igt_kms.h
> index 8810123fb..f696847a4 100644
> --- a/lib/igt_kms.h
> +++ b/lib/igt_kms.h
> @@ -1268,6 +1268,8 @@ bool igt_has_force_link_training_failure_debugfs(int drmfd, igt_output_t *output
>   int igt_get_dp_pending_lt_failures(int drm_fd, igt_output_t *output);
>   int igt_get_dp_pending_retrain(int drm_fd, igt_output_t *output);
>   void igt_reset_link_params(int drm_fd, igt_output_t *output);
> +void igt_set_link_params(int drm_fd, igt_output_t *output,
> +			   char *link_rate, char *lane_count);
>   int igt_backlight_read(int *result, const char *fname, igt_backlight_context_t *context);
>   int igt_backlight_write(int value, const char *fname, igt_backlight_context_t *context);
>