Re: [PATCH i-g-t v4 06/46] lib/igt_kms: Add helper to get a pipe from a connector

["Luca Ceresoli" <luca.ceresoli@bootlin.com>]

On Mon Nov 10, 2025 at 2:39 PM CET, Louis Chauvet wrote:
> Currently there is no way to get a pipe from the connector. Add this tiny
> helper that will try to get the currently used pipe for a specific
> connector.
>
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> ---
>  lib/igt_kms.c | 34 ++++++++++++++++++++++++++++++++++
>  lib/igt_kms.h |  8 ++++++++
>  2 files changed, 42 insertions(+)
>
> diff --git a/lib/igt_kms.c b/lib/igt_kms.c
> index c77c94d7c437..f8d4037a68bf 100644
> --- a/lib/igt_kms.c
> +++ b/lib/igt_kms.c
> @@ -7926,3 +7926,37 @@ int kms_wait_for_new_connectors(uint32_t **newly_connected,
>
>  	return newly_connected_count;
>  }
> +
> +enum pipe igt_get_pipe_from_connector(int drm_fd, int connector_id)

The function name suggests it takes a connector (a drmModeConnectorPtr
perhaps), but it takes a connector ID. I suggest renaming the function to
igt_get_pipe_from_connector_id() so that in case you need in the future a
function that takes a connector it will be intuitively named
igt_get_pipe_from_connector().

> +{
> +	drmModeObjectPropertiesPtr proplist;
> +	drmModePropertyPtr crtc_id_prop;
> +	drmModePropertyPtr prop;
> +	uint32_t crtc_id;
> +	enum pipe pipe_id;
> +	int i;
> +
> +	proplist = drmModeObjectGetProperties(drm_fd, connector_id, DRM_MODE_OBJECT_CONNECTOR);
> +	crtc_id_prop = NULL;
> +
> +	for (i = 0; i < proplist->count_props; i++) {
> +		prop = drmModeGetProperty(drm_fd, proplist->props[i]);
> +
> +		if (strcmp(prop->name, "CRTC_ID") == 0) {
> +			crtc_id_prop = prop;
> +			break;
> +		}
> +		drmModeFreeProperty(prop);
> +	}
> +
> +	igt_assert(crtc_id_prop);
> +	igt_assert((crtc_id_prop->flags & DRM_MODE_PROP_EXTENDED_TYPE) == DRM_MODE_PROP_OBJECT);
> +	crtc_id = proplist->prop_values[i];
> +	drmModeFreeProperty(crtc_id_prop);
> +	drmModeFreeObjectProperties(proplist);
> +	if (crtc_id != 0) {
> +		pipe_id = kmstest_get_pipe_from_crtc_id(drm_fd, crtc_id);
> +		return pipe_id;
> +	}
> +	return PIPE_NONE;
> +}
> diff --git a/lib/igt_kms.h b/lib/igt_kms.h
> index 7b1d01efebf2..4184c3930cbd 100644
> --- a/lib/igt_kms.h
> +++ b/lib/igt_kms.h
> @@ -1315,4 +1315,12 @@ int kms_wait_for_new_connectors(uint32_t **newly_connected,
>  int
>  get_list_diff(const uint32_t *list_a, int list_a_len, const uint32_t *list_b, int list_b_len,
>  	      uint32_t **diff);
> +/**
> + * igt_get_pipe_from_connector() - Get a pipe from the connector id
> + * @drm_fd: drm file descriptor to which the connector belongs
> + * @connector_id: connector to inspect
> + *
> + * Returns PIPE_NONE if the connector is not connected to any pipe
> + */

Documentation is before the function definition (.c) elsewhere, why at the
declaration in this case?

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com