[PATCH 09/11] drm/dp_mst: Add drm_dp_mst_aux_for_parent()

[Nautiyal, Ankit K]

On 3/21/2024 1:41 AM, Imre Deak wrote:
> Add a function to get the AUX device of the parent of an MST port, used
> by a follow-up i915 patch in the patchset.
>
> Cc: Lyude Paul <lyude at redhat.com>
> Cc: dri-devel at lists.freedesktop.org
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>   drivers/gpu/drm/display/drm_dp_mst_topology.c | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
>
> diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> index 6bd471a2266ce..d70f7de644371 100644
> --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> @@ -6004,6 +6004,22 @@ static bool drm_dp_mst_is_virtual_dpcd(struct drm_dp_mst_port *port)
>   	return false;
>   }
>   
> +/**
> + * drm_dp_mst_aux_for_parent() - Get the AUX device for an MST port's parent
> + * @port: MST port whose parent's AUX device is returned
> + *
> + * Return the AUX device for @port's parent or NULL if port's parent is the
> + * root port.
> + */
> +struct drm_dp_aux *drm_dp_mst_aux_for_parent(struct drm_dp_mst_port *port)
> +{
> +	if (!port->parent || !port->parent->port_parent)
> +		return NULL;
> +
> +	return &port->parent->port_parent->aux;
> +}
> +EXPORT_SYMBOL(drm_dp_mst_aux_for_parent);

As mentioned in previous patch, the declaration of this in the header, 
got included in previous patch.

Regards,

Ankit

> +
>   /**
>    * drm_dp_mst_dsc_aux_for_port() - Find the correct aux for DSC
>    * @port: The port to check. A leaf of the MST tree with an attached display.