Commit 38784f6f authored by Ville Syrjälä's avatar Ville Syrjälä
Browse files

drm/dp: Add helpers to identify downstream facing port types 



Add a few helpers to let us better identify which kind of DFP
we're dealing with.

v2: Use Returns: for kdoc (Lyude)

Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200904115354.25336-7-ville.syrjala@linux.intel.com


Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
Acked-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 530df3c0

drivers/gpu/drm/drm_dp_helper.c

+60 −0
Original line number Diff line number Diff line
@@ -363,6 +363,66 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, 
}

EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);



static bool is_edid_digital_input_dp(const struct edid *edid)

{

	return edid && edid->revision >= 4 &&

		edid->input & DRM_EDID_INPUT_DIGITAL &&

		(edid->input & DRM_EDID_DIGITAL_TYPE_MASK) == DRM_EDID_DIGITAL_TYPE_DP;

}



/**

 * drm_dp_downstream_is_type() - is the downstream facing port of certain type?

 * @dpcd: DisplayPort configuration data

 * @port_cap: port capabilities

 *

 * Caveat: Only works with DPCD 1.1+ port caps.

 *

 * Returns: whether the downstream facing port matches the type.

 */

bool drm_dp_downstream_is_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],

			       const u8 port_cap[4], u8 type)

{

	return drm_dp_is_branch(dpcd) &&

		dpcd[DP_DPCD_REV] >= 0x11 &&

		(port_cap[0] & DP_DS_PORT_TYPE_MASK) == type;

}

EXPORT_SYMBOL(drm_dp_downstream_is_type);



/**

 * drm_dp_downstream_is_tmds() - is the downstream facing port TMDS?

 * @dpcd: DisplayPort configuration data

 * @port_cap: port capabilities

 * @edid: EDID

 *

 * Returns: whether the downstream facing port is TMDS (HDMI/DVI).

 */

bool drm_dp_downstream_is_tmds(const u8 dpcd[DP_RECEIVER_CAP_SIZE],

			       const u8 port_cap[4],

			       const struct edid *edid)

{

	if (dpcd[DP_DPCD_REV] < 0x11) {

		switch (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK) {

		case DP_DWN_STRM_PORT_TYPE_TMDS:

			return true;

		default:

			return false;

		}

	}



	switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {

	case DP_DS_PORT_TYPE_DP_DUALMODE:

		if (is_edid_digital_input_dp(edid))

			return false;

		fallthrough;

	case DP_DS_PORT_TYPE_DVI:

	case DP_DS_PORT_TYPE_HDMI:

		return true;

	default:

		return false;

	}

}

EXPORT_SYMBOL(drm_dp_downstream_is_tmds);



/**

 * drm_dp_send_real_edid_checksum() - send back real edid checksum value

 * @aux: DisplayPort AUX channel

include/drm/drm_dp_helper.h

+5 −0
Original line number Diff line number Diff line
@@ -1638,6 +1638,11 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux, 
int drm_dp_read_downstream_info(struct drm_dp_aux *aux,

				const u8 dpcd[DP_RECEIVER_CAP_SIZE],

				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS]);

bool drm_dp_downstream_is_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],

			       const u8 port_cap[4], u8 type);

bool drm_dp_downstream_is_tmds(const u8 dpcd[DP_RECEIVER_CAP_SIZE],

			       const u8 port_cap[4],

			       const struct edid *edid);

int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],

				const u8 port_cap[4]);

int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],