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path: root/drivers/gpu/drm/drm_dp_helper.c
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Diffstat (limited to 'drivers/gpu/drm/drm_dp_helper.c')
-rw-r--r--drivers/gpu/drm/drm_dp_helper.c632
1 files changed, 590 insertions, 42 deletions
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index a3c82e726057..90807a6b415c 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -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
@@ -423,66 +483,313 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
}
EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
+static u8 drm_dp_downstream_port_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+ u8 port_count = dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_PORT_COUNT_MASK;
+
+ if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE && port_count > 4)
+ port_count = 4;
+
+ return port_count;
+}
+
+static int drm_dp_read_extended_dpcd_caps(struct drm_dp_aux *aux,
+ u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+ u8 dpcd_ext[6];
+ int ret;
+
+ /*
+ * Prior to DP1.3 the bit represented by
+ * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved.
+ * If it is set DP_DPCD_REV at 0000h could be at a value less than
+ * the true capability of the panel. The only way to check is to
+ * then compare 0000h and 2200h.
+ */
+ if (!(dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
+ DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT))
+ return 0;
+
+ ret = drm_dp_dpcd_read(aux, DP_DP13_DPCD_REV, &dpcd_ext,
+ sizeof(dpcd_ext));
+ if (ret < 0)
+ return ret;
+ if (ret != sizeof(dpcd_ext))
+ return -EIO;
+
+ if (dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) {
+ DRM_DEBUG_KMS("%s: Extended DPCD rev less than base DPCD rev (%d > %d)\n",
+ aux->name, dpcd[DP_DPCD_REV],
+ dpcd_ext[DP_DPCD_REV]);
+ return 0;
+ }
+
+ if (!memcmp(dpcd, dpcd_ext, sizeof(dpcd_ext)))
+ return 0;
+
+ DRM_DEBUG_KMS("%s: Base DPCD: %*ph\n",
+ aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
+
+ memcpy(dpcd, dpcd_ext, sizeof(dpcd_ext));
+
+ return 0;
+}
+
+/**
+ * drm_dp_read_dpcd_caps() - read DPCD caps and extended DPCD caps if
+ * available
+ * @aux: DisplayPort AUX channel
+ * @dpcd: Buffer to store the resulting DPCD in
+ *
+ * Attempts to read the base DPCD caps for @aux. Additionally, this function
+ * checks for and reads the extended DPRX caps (%DP_DP13_DPCD_REV) if
+ * present.
+ *
+ * Returns: %0 if the DPCD was read successfully, negative error code
+ * otherwise.
+ */
+int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
+ u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+ int ret;
+
+ ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
+ if (ret < 0)
+ return ret;
+ if (ret != DP_RECEIVER_CAP_SIZE || dpcd[DP_DPCD_REV] == 0)
+ return -EIO;
+
+ ret = drm_dp_read_extended_dpcd_caps(aux, dpcd);
+ if (ret < 0)
+ return ret;
+
+ DRM_DEBUG_KMS("%s: DPCD: %*ph\n",
+ aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
+
+ return ret;
+}
+EXPORT_SYMBOL(drm_dp_read_dpcd_caps);
+
/**
- * drm_dp_downstream_max_clock() - extract branch device max
- * pixel rate for legacy VGA
- * converter or max TMDS clock
- * rate for others
+ * drm_dp_read_downstream_info() - read DPCD downstream port info if available
+ * @aux: DisplayPort AUX channel
+ * @dpcd: A cached copy of the port's DPCD
+ * @downstream_ports: buffer to store the downstream port info in
+ *
+ * See also:
+ * drm_dp_downstream_max_clock()
+ * drm_dp_downstream_max_bpc()
+ *
+ * Returns: 0 if either the downstream port info was read successfully or
+ * there was no downstream info to read, or a negative error code otherwise.
+ */
+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])
+{
+ int ret;
+ u8 len;
+
+ memset(downstream_ports, 0, DP_MAX_DOWNSTREAM_PORTS);
+
+ /* No downstream info to read */
+ if (!drm_dp_is_branch(dpcd) ||
+ dpcd[DP_DPCD_REV] < DP_DPCD_REV_10 ||
+ !(dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT))
+ return 0;
+
+ len = drm_dp_downstream_port_count(dpcd);
+ if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE)
+ len *= 4;
+
+ ret = drm_dp_dpcd_read(aux, DP_DOWNSTREAM_PORT_0, downstream_ports, len);
+ if (ret < 0)
+ return ret;
+ if (ret != len)
+ return -EIO;
+
+ DRM_DEBUG_KMS("%s: DPCD DFP: %*ph\n",
+ aux->name, len, downstream_ports);
+
+ return 0;
+}
+EXPORT_SYMBOL(drm_dp_read_downstream_info);
+
+/**
+ * drm_dp_downstream_max_dotclock() - extract downstream facing port max dot clock
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*
- * Returns max clock in kHz on success or 0 if max clock not defined
+ * Returns: Downstream facing port max dot clock in kHz on success,
+ * or 0 if max clock not defined
*/
-int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
- const u8 port_cap[4])
+int drm_dp_downstream_max_dotclock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4])
{
- int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
- bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
- DP_DETAILED_CAP_INFO_AVAILABLE;
+ if (!drm_dp_is_branch(dpcd))
+ return 0;
- if (!detailed_cap_info)
+ if (dpcd[DP_DPCD_REV] < 0x11)
return 0;
- switch (type) {
+ switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_VGA:
- return port_cap[1] * 8 * 1000;
- case DP_DS_PORT_TYPE_DVI:
- case DP_DS_PORT_TYPE_HDMI:
+ if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
+ return 0;
+ return port_cap[1] * 8000;
+ default:
+ return 0;
+ }
+}
+EXPORT_SYMBOL(drm_dp_downstream_max_dotclock);
+
+/**
+ * drm_dp_downstream_max_tmds_clock() - extract downstream facing port max TMDS clock
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: port capabilities
+ * @edid: EDID
+ *
+ * Returns: HDMI/DVI downstream facing port max TMDS clock in kHz on success,
+ * or 0 if max TMDS clock not defined
+ */
+int drm_dp_downstream_max_tmds_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4],
+ const struct edid *edid)
+{
+ if (!drm_dp_is_branch(dpcd))
+ return 0;
+
+ 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 165000;
+ default:
+ return 0;
+ }
+ }
+
+ switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
case DP_DS_PORT_TYPE_DP_DUALMODE:
+ if (is_edid_digital_input_dp(edid))
+ return 0;
+ /*
+ * It's left up to the driver to check the
+ * DP dual mode adapter's max TMDS clock.
+ *
+ * Unfortunatley it looks like branch devices
+ * may not fordward that the DP dual mode i2c
+ * access so we just usually get i2c nak :(
+ */
+ fallthrough;
+ case DP_DS_PORT_TYPE_HDMI:
+ /*
+ * We should perhaps assume 165 MHz when detailed cap
+ * info is not available. But looks like many typical
+ * branch devices fall into that category and so we'd
+ * probably end up with users complaining that they can't
+ * get high resolution modes with their favorite dongle.
+ *
+ * So let's limit to 300 MHz instead since DPCD 1.4
+ * HDMI 2.0 DFPs are required to have the detailed cap
+ * info. So it's more likely we're dealing with a HDMI 1.4
+ * compatible* device here.
+ */
+ if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
+ return 300000;
+ return port_cap[1] * 2500;
+ case DP_DS_PORT_TYPE_DVI:
+ if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
+ return 165000;
+ /* FIXME what to do about DVI dual link? */
return port_cap[1] * 2500;
default:
return 0;
}
}
-EXPORT_SYMBOL(drm_dp_downstream_max_clock);
+EXPORT_SYMBOL(drm_dp_downstream_max_tmds_clock);
/**
- * drm_dp_downstream_max_bpc() - extract branch device max
- * bits per component
+ * drm_dp_downstream_min_tmds_clock() - extract downstream facing port min TMDS clock
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
+ * @edid: EDID
*
- * Returns max bpc on success or 0 if max bpc not defined
+ * Returns: HDMI/DVI downstream facing port min TMDS clock in kHz on success,
+ * or 0 if max TMDS clock not defined
*/
-int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
- const u8 port_cap[4])
+int drm_dp_downstream_min_tmds_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4],
+ const struct edid *edid)
{
- int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
- bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
- DP_DETAILED_CAP_INFO_AVAILABLE;
- int bpc;
-
- if (!detailed_cap_info)
+ if (!drm_dp_is_branch(dpcd))
return 0;
- switch (type) {
- case DP_DS_PORT_TYPE_VGA:
+ 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 25000;
+ default:
+ return 0;
+ }
+ }
+
+ switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
+ case DP_DS_PORT_TYPE_DP_DUALMODE:
+ if (is_edid_digital_input_dp(edid))
+ return 0;
+ fallthrough;
case DP_DS_PORT_TYPE_DVI:
case DP_DS_PORT_TYPE_HDMI:
+ /*
+ * Unclear whether the protocol converter could
+ * utilize pixel replication. Assume it won't.
+ */
+ return 25000;
+ default:
+ return 0;
+ }
+}
+EXPORT_SYMBOL(drm_dp_downstream_min_tmds_clock);
+
+/**
+ * drm_dp_downstream_max_bpc() - extract downstream facing port max
+ * bits per component
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: downstream facing port capabilities
+ * @edid: EDID
+ *
+ * Returns: Max bpc on success or 0 if max bpc not defined
+ */
+int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4],
+ const struct edid *edid)
+{
+ if (!drm_dp_is_branch(dpcd))
+ return 0;
+
+ if (dpcd[DP_DPCD_REV] < 0x11) {
+ switch (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK) {
+ case DP_DWN_STRM_PORT_TYPE_DP:
+ return 0;
+ default:
+ return 8;
+ }
+ }
+
+ switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
+ case DP_DS_PORT_TYPE_DP:
+ return 0;
case DP_DS_PORT_TYPE_DP_DUALMODE:
- bpc = port_cap[2] & DP_DS_MAX_BPC_MASK;
+ if (is_edid_digital_input_dp(edid))
+ return 0;
+ fallthrough;
+ case DP_DS_PORT_TYPE_HDMI:
+ case DP_DS_PORT_TYPE_DVI:
+ case DP_DS_PORT_TYPE_VGA:
+ if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
+ return 8;
- switch (bpc) {
+ switch (port_cap[2] & DP_DS_MAX_BPC_MASK) {
case DP_DS_8BPC:
return 8;
case DP_DS_10BPC:
@@ -491,15 +798,131 @@ int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
return 12;
case DP_DS_16BPC:
return 16;
+ default:
+ return 8;
}
- /* fall through */
+ break;
default:
- return 0;
+ return 8;
}
}
EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
/**
+ * drm_dp_downstream_420_passthrough() - determine downstream facing port
+ * YCbCr 4:2:0 pass-through capability
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: downstream facing port capabilities
+ *
+ * Returns: whether the downstream facing port can pass through YCbCr 4:2:0
+ */
+bool drm_dp_downstream_420_passthrough(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4])
+{
+ if (!drm_dp_is_branch(dpcd))
+ return false;
+
+ if (dpcd[DP_DPCD_REV] < 0x13)
+ return false;
+
+ switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
+ case DP_DS_PORT_TYPE_DP:
+ return true;
+ case DP_DS_PORT_TYPE_HDMI:
+ if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
+ return false;
+
+ return port_cap[3] & DP_DS_HDMI_YCBCR420_PASS_THROUGH;
+ default:
+ return false;
+ }
+}
+EXPORT_SYMBOL(drm_dp_downstream_420_passthrough);
+
+/**
+ * drm_dp_downstream_444_to_420_conversion() - determine downstream facing port
+ * YCbCr 4:4:4->4:2:0 conversion capability
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: downstream facing port capabilities
+ *
+ * Returns: whether the downstream facing port can convert YCbCr 4:4:4 to 4:2:0
+ */
+bool drm_dp_downstream_444_to_420_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4])
+{
+ if (!drm_dp_is_branch(dpcd))
+ return false;
+
+ if (dpcd[DP_DPCD_REV] < 0x13)
+ return false;
+
+ switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
+ case DP_DS_PORT_TYPE_HDMI:
+ if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
+ return false;
+
+ return port_cap[3] & DP_DS_HDMI_YCBCR444_TO_420_CONV;
+ default:
+ return false;
+ }
+}
+EXPORT_SYMBOL(drm_dp_downstream_444_to_420_conversion);
+
+/**
+ * drm_dp_downstream_mode() - return a mode for downstream facing port
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: port capabilities
+ *
+ * Provides a suitable mode for downstream facing ports without EDID.
+ *
+ * Returns: A new drm_display_mode on success or NULL on failure
+ */
+struct drm_display_mode *
+drm_dp_downstream_mode(struct drm_device *dev,
+ const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4])
+
+{
+ u8 vic;
+
+ if (!drm_dp_is_branch(dpcd))
+ return NULL;
+
+ if (dpcd[DP_DPCD_REV] < 0x11)
+ return NULL;
+
+ switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
+ case DP_DS_PORT_TYPE_NON_EDID:
+ switch (port_cap[0] & DP_DS_NON_EDID_MASK) {
+ case DP_DS_NON_EDID_720x480i_60:
+ vic = 6;
+ break;
+ case DP_DS_NON_EDID_720x480i_50:
+ vic = 21;
+ break;
+ case DP_DS_NON_EDID_1920x1080i_60:
+ vic = 5;
+ break;
+ case DP_DS_NON_EDID_1920x1080i_50:
+ vic = 20;
+ break;
+ case DP_DS_NON_EDID_1280x720_60:
+ vic = 4;
+ break;
+ case DP_DS_NON_EDID_1280x720_50:
+ vic = 19;
+ break;
+ default:
+ return NULL;
+ }
+ return drm_display_mode_from_cea_vic(dev, vic);
+ default:
+ return NULL;
+ }
+}
+EXPORT_SYMBOL(drm_dp_downstream_mode);
+
+/**
* drm_dp_downstream_id() - identify branch device
* @aux: DisplayPort AUX channel
* @id: DisplayPort branch device id
@@ -517,12 +940,15 @@ EXPORT_SYMBOL(drm_dp_downstream_id);
* @m: pointer for debugfs file
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
+ * @edid: EDID
* @aux: DisplayPort AUX channel
*
*/
void drm_dp_downstream_debug(struct seq_file *m,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
- const u8 port_cap[4], struct drm_dp_aux *aux)
+ const u8 port_cap[4],
+ const struct edid *edid,
+ struct drm_dp_aux *aux)
{
bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
DP_DETAILED_CAP_INFO_AVAILABLE;
@@ -580,16 +1006,19 @@ void drm_dp_downstream_debug(struct seq_file *m,
seq_printf(m, "\t\tSW: %d.%d\n", rev[0], rev[1]);
if (detailed_cap_info) {
- clk = drm_dp_downstream_max_clock(dpcd, port_cap);
+ clk = drm_dp_downstream_max_dotclock(dpcd, port_cap);
+ if (clk > 0)
+ seq_printf(m, "\t\tMax dot clock: %d kHz\n", clk);
- if (clk > 0) {
- if (type == DP_DS_PORT_TYPE_VGA)
- seq_printf(m, "\t\tMax dot clock: %d kHz\n", clk);
- else
- seq_printf(m, "\t\tMax TMDS clock: %d kHz\n", clk);
- }
+ clk = drm_dp_downstream_max_tmds_clock(dpcd, port_cap, edid);
+ if (clk > 0)
+ seq_printf(m, "\t\tMax TMDS clock: %d kHz\n", clk);
+
+ clk = drm_dp_downstream_min_tmds_clock(dpcd, port_cap, edid);
+ if (clk > 0)
+ seq_printf(m, "\t\tMin TMDS clock: %d kHz\n", clk);
- bpc = drm_dp_downstream_max_bpc(dpcd, port_cap);
+ bpc = drm_dp_downstream_max_bpc(dpcd, port_cap, edid);
if (bpc > 0)
seq_printf(m, "\t\tMax bpc: %d\n", bpc);
@@ -597,6 +1026,125 @@ void drm_dp_downstream_debug(struct seq_file *m,
}
EXPORT_SYMBOL(drm_dp_downstream_debug);
+/**
+ * drm_dp_subconnector_type() - get DP branch device type
+ *
+ */
+enum drm_mode_subconnector
+drm_dp_subconnector_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4])
+{
+ int type;
+ if (!drm_dp_is_branch(dpcd))
+ return DRM_MODE_SUBCONNECTOR_Native;
+ /* DP 1.0 approach */
+ if (dpcd[DP_DPCD_REV] == DP_DPCD_REV_10) {
+ type = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
+ DP_DWN_STRM_PORT_TYPE_MASK;
+
+ switch (type) {
+ case DP_DWN_STRM_PORT_TYPE_TMDS:
+ /* Can be HDMI or DVI-D, DVI-D is a safer option */
+ return DRM_MODE_SUBCONNECTOR_DVID;
+ case DP_DWN_STRM_PORT_TYPE_ANALOG:
+ /* Can be VGA or DVI-A, VGA is more popular */
+ return DRM_MODE_SUBCONNECTOR_VGA;
+ case DP_DWN_STRM_PORT_TYPE_DP:
+ return DRM_MODE_SUBCONNECTOR_DisplayPort;
+ case DP_DWN_STRM_PORT_TYPE_OTHER:
+ default:
+ return DRM_MODE_SUBCONNECTOR_Unknown;
+ }
+ }
+ type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
+
+ switch (type) {
+ case DP_DS_PORT_TYPE_DP:
+ case DP_DS_PORT_TYPE_DP_DUALMODE:
+ return DRM_MODE_SUBCONNECTOR_DisplayPort;
+ case DP_DS_PORT_TYPE_VGA:
+ return DRM_MODE_SUBCONNECTOR_VGA;
+ case DP_DS_PORT_TYPE_DVI:
+ return DRM_MODE_SUBCONNECTOR_DVID;
+ case DP_DS_PORT_TYPE_HDMI:
+ return DRM_MODE_SUBCONNECTOR_HDMIA;
+ case DP_DS_PORT_TYPE_WIRELESS:
+ return DRM_MODE_SUBCONNECTOR_Wireless;
+ case DP_DS_PORT_TYPE_NON_EDID:
+ default:
+ return DRM_MODE_SUBCONNECTOR_Unknown;
+ }
+}
+EXPORT_SYMBOL(drm_dp_subconnector_type);
+
+/**
+ * drm_mode_set_dp_subconnector_property - set subconnector for DP connector
+ *
+ * Called by a driver on every detect event.
+ */
+void drm_dp_set_subconnector_property(struct drm_connector *connector,
+ enum drm_connector_status status,
+ const u8 *dpcd,
+ const u8 port_cap[4])
+{
+ enum drm_mode_subconnector subconnector = DRM_MODE_SUBCONNECTOR_Unknown;
+
+ if (status == connector_status_connected)
+ subconnector = drm_dp_subconnector_type(dpcd, port_cap);
+ drm_object_property_set_value(&connector->base,
+ connector->dev->mode_config.dp_subconnector_property,
+ subconnector);
+}
+EXPORT_SYMBOL(drm_dp_set_subconnector_property);
+
+/**
+ * drm_dp_read_sink_count_cap() - Check whether a given connector has a valid sink
+ * count
+ * @connector: The DRM connector to check
+ * @dpcd: A cached copy of the connector's DPCD RX capabilities
+ * @desc: A cached copy of the connector's DP descriptor
+ *
+ * See also: drm_dp_read_sink_count()
+ *
+ * Returns: %True if the (e)DP connector has a valid sink count that should
+ * be probed, %false otherwise.
+ */
+bool drm_dp_read_sink_count_cap(struct drm_connector *connector,
+ const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const struct drm_dp_desc *desc)
+{
+ /* Some eDP panels don't set a valid value for the sink count */
+ return connector->connector_type != DRM_MODE_CONNECTOR_eDP &&
+ dpcd[DP_DPCD_REV] >= DP_DPCD_REV_11 &&
+ dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT &&
+ !drm_dp_has_quirk(desc, 0, DP_DPCD_QUIRK_NO_SINK_COUNT);
+}
+EXPORT_SYMBOL(drm_dp_read_sink_count_cap);
+
+/**
+ * drm_dp_read_sink_count() - Retrieve the sink count for a given sink
+ * @aux: The DP AUX channel to use
+ *
+ * See also: drm_dp_read_sink_count_cap()
+ *
+ * Returns: The current sink count reported by @aux, or a negative error code
+ * otherwise.
+ */
+int drm_dp_read_sink_count(struct drm_dp_aux *aux)
+{
+ u8 count;
+ int ret;
+
+ ret = drm_dp_dpcd_readb(aux, DP_SINK_COUNT, &count);
+ if (ret < 0)
+ return ret;
+ if (ret != 1)
+ return -EIO;
+
+ return DP_GET_SINK_COUNT(count);
+}
+EXPORT_SYMBOL(drm_dp_read_sink_count);
+
/*
* I2C-over-AUX implementation
*/