[PATCH v8 2/6] drm/dp_mst: Parse FEC capability on MST ports

[Harry Wentland]

On 2019-08-26 2:05 p.m., David Francis wrote:
> As of DP1.4, ENUM_PATH_RESOURCES returns a bit indicating
> if FEC can be supported up to that point in the MST network.
> 
> The bit is the first byte of the ENUM_PATH_RESOURCES ack reply,
> bottom-most bit (refer to section 2.11.9.4 of DP standard,
> v1.4)
> 
> That value is needed for FEC and DSC support
> 
> Store it on drm_dp_mst_port
> 
> Signed-off-by: David Francis <David.Francis at amd.com>
> Reviewed-by: Lyude Paul <lyude at redhat.com>

Reviewed-by: Harry Wentland <harry.wentland at amd.com>

Harry

> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c | 2 ++
>  include/drm/drm_dp_mst_helper.h       | 3 +++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 3e7b7553cf4d..9f3604355705 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -553,6 +553,7 @@ static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband
>  {
>  	int idx = 1;
>  	repmsg->u.path_resources.port_number = (raw->msg[idx] >> 4) & 0xf;
> +	repmsg->u.path_resources.fec_capable = raw->msg[idx] & 0x1;
>  	idx++;
>  	if (idx > raw->curlen)
>  		goto fail_len;
> @@ -2183,6 +2184,7 @@ static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
>  			DRM_DEBUG_KMS("enum path resources %d: %d %d\n", txmsg->reply.u.path_resources.port_number, txmsg->reply.u.path_resources.full_payload_bw_number,
>  			       txmsg->reply.u.path_resources.avail_payload_bw_number);
>  			port->available_pbn = txmsg->reply.u.path_resources.avail_payload_bw_number;
> +			port->fec_capable = txmsg->reply.u.path_resources.fec_capable;
>  		}
>  	}
>  
> diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
> index 9116b2c95239..f113ae04fa88 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -108,6 +108,8 @@ struct drm_dp_mst_port {
>  	 * audio-capable.
>  	 */
>  	bool has_audio;
> +
> +	bool fec_capable;
>  };
>  
>  /**
> @@ -312,6 +314,7 @@ struct drm_dp_port_number_req {
>  
>  struct drm_dp_enum_path_resources_ack_reply {
>  	u8 port_number;
> +	bool fec_capable;
>  	u16 full_payload_bw_number;
>  	u16 avail_payload_bw_number;
>  };
>