Merge tag 'topic/dp-hdmi-2.1-pcon-2020-12-23' of git://anongit.freedesktop.org/drm/drm-intel into drm-next

Add support for DP-HDMI2.1 PCON

From the series cover letter:

This patch series attempts to add support for a DP-HDMI2.1 Protocol
Convertor. The VESA spec for the HDMI2.1 PCON are proposed in Errata
E5 to DisplayPort_v2.0:
https://vesa.org/join-vesamemberships/member-downloads/?action=stamp&fileid=42299
The details are mentioned in:
VESA DP-to-HDMI PCON Specification Standalone Document
https://groups.vesa.org/wg/DP/document/15651

This series starts with adding support for FRL (Fixed Rate Link)
Training between the PCON and HDMI2.1 sink.
As per HDMI2.1 specification, a new data-channel or lane is added in
FRL mode, by repurposing the TMDS clock Channel. Through FRL, higher
bit-rate can be supported, ie. up to 12 Gbps/lane (48 Gbps over 4
lanes).

With these patches, the HDMI2.1 PCON can be configured to achieve FRL
training based on the maximum FRL rate supported by the panel, source
and the PCON.
The approach is to add the support for FRL training between PCON and
HDMI2.1 sink and gradually add other blocks for supporting higher
resolutions and other HDMI2.1 features, that can be supported by pcon
for the sources that do not natively support HDMI2.1.

This is done before the DP Link training between the source and PCON
is started. In case of FRL training is not achieved, the PCON will
work in the regular TMDS mode, without HDMI2.1 feature support.
Any interruption in FRL training between the PCON and HDMI2.1 sink is
notified through IRQ_HPD. On receiving the IRQ_HPD the concerned DPCD
registers are read and FRL training is re-attempted.

Currently, we have tested the FRL training and are able to enable 4K
display with TGL Platform + Realtek PCON RTD2173 with HDMI2.1 supporting
panel.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
From: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/87lfdpndkt.fsf@intel.com

1 files changed, 566 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 5bd0934004e3..3ecde451f523 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -950,6 +950,38 @@ bool drm_dp_downstream_444_to_420_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZE]
 EXPORT_SYMBOL(drm_dp_downstream_444_to_420_conversion);
 
 /**
+ * drm_dp_downstream_rgb_to_ycbcr_conversion() - determine downstream facing port
+ *                                               RGB->YCbCr conversion capability
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: downstream facing port capabilities
+ * @colorspc: Colorspace for which conversion cap is sought
+ *
+ * Returns: whether the downstream facing port can convert RGB->YCbCr for a given
+ * colorspace.
+ */
+bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+					       const u8 port_cap[4],
+					       u8 color_spc)
+{
+	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] & color_spc;
+	default:
+		return false;
+	}
+}
+EXPORT_SYMBOL(drm_dp_downstream_rgb_to_ycbcr_conversion);
+
+/**
  * drm_dp_downstream_mode() - return a mode for downstream facing port
  * @dev: DRM device
  * @dpcd: DisplayPort configuration data
@@ -2596,3 +2628,537 @@ void drm_dp_vsc_sdp_log(const char *level, struct device *dev,
 #undef DP_SDP_LOG
 }
 EXPORT_SYMBOL(drm_dp_vsc_sdp_log);
+
+/**
+ * drm_dp_get_pcon_max_frl_bw() - maximum frl supported by PCON
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: port capabilities
+ *
+ * Returns maximum frl bandwidth supported by PCON in GBPS,
+ * returns 0 if not supported.
+ */
+int drm_dp_get_pcon_max_frl_bw(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+			       const u8 port_cap[4])
+{
+	int bw;
+	u8 buf;
+
+	buf = port_cap[2];
+	bw = buf & DP_PCON_MAX_FRL_BW;
+
+	switch (bw) {
+	case DP_PCON_MAX_9GBPS:
+		return 9;
+	case DP_PCON_MAX_18GBPS:
+		return 18;
+	case DP_PCON_MAX_24GBPS:
+		return 24;
+	case DP_PCON_MAX_32GBPS:
+		return 32;
+	case DP_PCON_MAX_40GBPS:
+		return 40;
+	case DP_PCON_MAX_48GBPS:
+		return 48;
+	case DP_PCON_MAX_0GBPS:
+	default:
+		return 0;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_get_pcon_max_frl_bw);
+
+/**
+ * drm_dp_pcon_frl_prepare() - Prepare PCON for FRL.
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns 0 if success, else returns negative error code.
+ */
+int drm_dp_pcon_frl_prepare(struct drm_dp_aux *aux, bool enable_frl_ready_hpd)
+{
+	int ret;
+	u8 buf = DP_PCON_ENABLE_SOURCE_CTL_MODE |
+		 DP_PCON_ENABLE_LINK_FRL_MODE;
+
+	if (enable_frl_ready_hpd)
+		buf |= DP_PCON_ENABLE_HPD_READY;
+
+	ret = drm_dp_dpcd_writeb(aux, DP_PCON_HDMI_LINK_CONFIG_1, buf);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_pcon_frl_prepare);
+
+/**
+ * drm_dp_pcon_is_frl_ready() - Is PCON ready for FRL
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns true if success, else returns false.
+ */
+bool drm_dp_pcon_is_frl_ready(struct drm_dp_aux *aux)
+{
+	int ret;
+	u8 buf;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PCON_HDMI_TX_LINK_STATUS, &buf);
+	if (ret < 0)
+		return false;
+
+	if (buf & DP_PCON_FRL_READY)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL(drm_dp_pcon_is_frl_ready);
+
+/**
+ * drm_dp_pcon_frl_configure_1() - Set HDMI LINK Configuration-Step1
+ * @aux: DisplayPort AUX channel
+ * @max_frl_gbps: maximum frl bw to be configured between PCON and HDMI sink
+ * @concurrent_mode: true if concurrent mode or operation is required,
+ * false otherwise.
+ *
+ * Returns 0 if success, else returns negative error code.
+ */
+
+int drm_dp_pcon_frl_configure_1(struct drm_dp_aux *aux, int max_frl_gbps,
+				bool concurrent_mode)
+{
+	int ret;
+	u8 buf;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PCON_HDMI_LINK_CONFIG_1, &buf);
+	if (ret < 0)
+		return ret;
+
+	if (concurrent_mode)
+		buf |= DP_PCON_ENABLE_CONCURRENT_LINK;
+	else
+		buf &= ~DP_PCON_ENABLE_CONCURRENT_LINK;
+
+	switch (max_frl_gbps) {
+	case 9:
+		buf |=  DP_PCON_ENABLE_MAX_BW_9GBPS;
+		break;
+	case 18:
+		buf |=  DP_PCON_ENABLE_MAX_BW_18GBPS;
+		break;
+	case 24:
+		buf |=  DP_PCON_ENABLE_MAX_BW_24GBPS;
+		break;
+	case 32:
+		buf |=  DP_PCON_ENABLE_MAX_BW_32GBPS;
+		break;
+	case 40:
+		buf |=  DP_PCON_ENABLE_MAX_BW_40GBPS;
+		break;
+	case 48:
+		buf |=  DP_PCON_ENABLE_MAX_BW_48GBPS;
+		break;
+	case 0:
+		buf |=  DP_PCON_ENABLE_MAX_BW_0GBPS;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = drm_dp_dpcd_writeb(aux, DP_PCON_HDMI_LINK_CONFIG_1, buf);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_frl_configure_1);
+
+/**
+ * drm_dp_pcon_frl_configure_2() - Set HDMI Link configuration Step-2
+ * @aux: DisplayPort AUX channel
+ * @max_frl_mask : Max FRL BW to be tried by the PCON with HDMI Sink
+ * @extended_train_mode : true for Extended Mode, false for Normal Mode.
+ * In Normal mode, the PCON tries each frl bw from the max_frl_mask starting
+ * from min, and stops when link training is successful. In Extended mode, all
+ * frl bw selected in the mask are trained by the PCON.
+ *
+ * Returns 0 if success, else returns negative error code.
+ */
+int drm_dp_pcon_frl_configure_2(struct drm_dp_aux *aux, int max_frl_mask,
+				bool extended_train_mode)
+{
+	int ret;
+	u8 buf = max_frl_mask;
+
+	if (extended_train_mode)
+		buf |= DP_PCON_FRL_LINK_TRAIN_EXTENDED;
+
+	ret = drm_dp_dpcd_writeb(aux, DP_PCON_HDMI_LINK_CONFIG_2, buf);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_frl_configure_2);
+
+/**
+ * drm_dp_pcon_reset_frl_config() - Re-Set HDMI Link configuration.
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns 0 if success, else returns negative error code.
+ */
+int drm_dp_pcon_reset_frl_config(struct drm_dp_aux *aux)
+{
+	int ret;
+
+	ret = drm_dp_dpcd_writeb(aux, DP_PCON_HDMI_LINK_CONFIG_1, 0x0);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_reset_frl_config);
+
+/**
+ * drm_dp_pcon_frl_enable() - Enable HDMI link through FRL
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns 0 if success, else returns negative error code.
+ */
+int drm_dp_pcon_frl_enable(struct drm_dp_aux *aux)
+{
+	int ret;
+	u8 buf = 0;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PCON_HDMI_LINK_CONFIG_1, &buf);
+	if (ret < 0)
+		return ret;
+	if (!(buf & DP_PCON_ENABLE_SOURCE_CTL_MODE)) {
+		DRM_DEBUG_KMS("PCON in Autonomous mode, can't enable FRL\n");
+		return -EINVAL;
+	}
+	buf |= DP_PCON_ENABLE_HDMI_LINK;
+	ret = drm_dp_dpcd_writeb(aux, DP_PCON_HDMI_LINK_CONFIG_1, buf);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_frl_enable);
+
+/**
+ * drm_dp_pcon_hdmi_link_active() - check if the PCON HDMI LINK status is active.
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns true if link is active else returns false.
+ */
+bool drm_dp_pcon_hdmi_link_active(struct drm_dp_aux *aux)
+{
+	u8 buf;
+	int ret;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PCON_HDMI_TX_LINK_STATUS, &buf);
+	if (ret < 0)
+		return false;
+
+	return buf & DP_PCON_HDMI_TX_LINK_ACTIVE;
+}
+EXPORT_SYMBOL(drm_dp_pcon_hdmi_link_active);
+
+/**
+ * drm_dp_pcon_hdmi_link_mode() - get the PCON HDMI LINK MODE
+ * @aux: DisplayPort AUX channel
+ * @frl_trained_mask: pointer to store bitmask of the trained bw configuration.
+ * Valid only if the MODE returned is FRL. For Normal Link training mode
+ * only 1 of the bits will be set, but in case of Extended mode, more than
+ * one bits can be set.
+ *
+ * Returns the link mode : TMDS or FRL on success, else returns negative error
+ * code.
+ */
+int drm_dp_pcon_hdmi_link_mode(struct drm_dp_aux *aux, u8 *frl_trained_mask)
+{
+	u8 buf;
+	int mode;
+	int ret;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PCON_HDMI_POST_FRL_STATUS, &buf);
+	if (ret < 0)
+		return ret;
+
+	mode = buf & DP_PCON_HDMI_LINK_MODE;
+
+	if (frl_trained_mask && DP_PCON_HDMI_MODE_FRL == mode)
+		*frl_trained_mask = (buf & DP_PCON_HDMI_FRL_TRAINED_BW) >> 1;
+
+	return mode;
+}
+EXPORT_SYMBOL(drm_dp_pcon_hdmi_link_mode);
+
+/**
+ * drm_dp_pcon_hdmi_frl_link_error_count() - print the error count per lane
+ * during link failure between PCON and HDMI sink
+ * @aux: DisplayPort AUX channel
+ * @connector: DRM connector
+ * code.
+ **/
+
+void drm_dp_pcon_hdmi_frl_link_error_count(struct drm_dp_aux *aux,
+					   struct drm_connector *connector)
+{
+	u8 buf, error_count;
+	int i, num_error;
+	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
+
+	for (i = 0; i < hdmi->max_lanes; i++) {
+		if (drm_dp_dpcd_readb(aux, DP_PCON_HDMI_ERROR_STATUS_LN0 + i, &buf) < 0)
+			return;
+
+		error_count = buf & DP_PCON_HDMI_ERROR_COUNT_MASK;
+		switch (error_count) {
+		case DP_PCON_HDMI_ERROR_COUNT_HUNDRED_PLUS:
+			num_error = 100;
+			break;
+		case DP_PCON_HDMI_ERROR_COUNT_TEN_PLUS:
+			num_error = 10;
+			break;
+		case DP_PCON_HDMI_ERROR_COUNT_THREE_PLUS:
+			num_error = 3;
+			break;
+		default:
+			num_error = 0;
+		}
+
+		DRM_ERROR("More than %d errors since the last read for lane %d", num_error, i);
+	}
+}
+EXPORT_SYMBOL(drm_dp_pcon_hdmi_frl_link_error_count);
+
+/*
+ * drm_dp_pcon_enc_is_dsc_1_2 - Does PCON Encoder supports DSC 1.2
+ * @pcon_dsc_dpcd: DSC capabilities of the PCON DSC Encoder
+ *
+ * Returns true is PCON encoder is DSC 1.2 else returns false.
+ */
+bool drm_dp_pcon_enc_is_dsc_1_2(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE])
+{
+	u8 buf;
+	u8 major_v, minor_v;
+
+	buf = pcon_dsc_dpcd[DP_PCON_DSC_VERSION - DP_PCON_DSC_ENCODER];
+	major_v = (buf & DP_PCON_DSC_MAJOR_MASK) >> DP_PCON_DSC_MAJOR_SHIFT;
+	minor_v = (buf & DP_PCON_DSC_MINOR_MASK) >> DP_PCON_DSC_MINOR_SHIFT;
+
+	if (major_v == 1 && minor_v == 2)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL(drm_dp_pcon_enc_is_dsc_1_2);
+
+/*
+ * drm_dp_pcon_dsc_max_slices - Get max slices supported by PCON DSC Encoder
+ * @pcon_dsc_dpcd: DSC capabilities of the PCON DSC Encoder
+ *
+ * Returns maximum no. of slices supported by the PCON DSC Encoder.
+ */
+int drm_dp_pcon_dsc_max_slices(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE])
+{
+	u8 slice_cap1, slice_cap2;
+
+	slice_cap1 = pcon_dsc_dpcd[DP_PCON_DSC_SLICE_CAP_1 - DP_PCON_DSC_ENCODER];
+	slice_cap2 = pcon_dsc_dpcd[DP_PCON_DSC_SLICE_CAP_2 - DP_PCON_DSC_ENCODER];
+
+	if (slice_cap2 & DP_PCON_DSC_24_PER_DSC_ENC)
+		return 24;
+	if (slice_cap2 & DP_PCON_DSC_20_PER_DSC_ENC)
+		return 20;
+	if (slice_cap2 & DP_PCON_DSC_16_PER_DSC_ENC)
+		return 16;
+	if (slice_cap1 & DP_PCON_DSC_12_PER_DSC_ENC)
+		return 12;
+	if (slice_cap1 & DP_PCON_DSC_10_PER_DSC_ENC)
+		return 10;
+	if (slice_cap1 & DP_PCON_DSC_8_PER_DSC_ENC)
+		return 8;
+	if (slice_cap1 & DP_PCON_DSC_6_PER_DSC_ENC)
+		return 6;
+	if (slice_cap1 & DP_PCON_DSC_4_PER_DSC_ENC)
+		return 4;
+	if (slice_cap1 & DP_PCON_DSC_2_PER_DSC_ENC)
+		return 2;
+	if (slice_cap1 & DP_PCON_DSC_1_PER_DSC_ENC)
+		return 1;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_dsc_max_slices);
+
+/*
+ * drm_dp_pcon_dsc_max_slice_width() - Get max slice width for Pcon DSC encoder
+ * @pcon_dsc_dpcd: DSC capabilities of the PCON DSC Encoder
+ *
+ * Returns maximum width of the slices in pixel width i.e. no. of pixels x 320.
+ */
+int drm_dp_pcon_dsc_max_slice_width(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE])
+{
+	u8 buf;
+
+	buf = pcon_dsc_dpcd[DP_PCON_DSC_MAX_SLICE_WIDTH - DP_PCON_DSC_ENCODER];
+
+	return buf * DP_DSC_SLICE_WIDTH_MULTIPLIER;
+}
+EXPORT_SYMBOL(drm_dp_pcon_dsc_max_slice_width);
+
+/*
+ * drm_dp_pcon_dsc_bpp_incr() - Get bits per pixel increment for PCON DSC encoder
+ * @pcon_dsc_dpcd: DSC capabilities of the PCON DSC Encoder
+ *
+ * Returns the bpp precision supported by the PCON encoder.
+ */
+int drm_dp_pcon_dsc_bpp_incr(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE])
+{
+	u8 buf;
+
+	buf = pcon_dsc_dpcd[DP_PCON_DSC_BPP_INCR - DP_PCON_DSC_ENCODER];
+
+	switch (buf & DP_PCON_DSC_BPP_INCR_MASK) {
+	case DP_PCON_DSC_ONE_16TH_BPP:
+		return 16;
+	case DP_PCON_DSC_ONE_8TH_BPP:
+		return 8;
+	case DP_PCON_DSC_ONE_4TH_BPP:
+		return 4;
+	case DP_PCON_DSC_ONE_HALF_BPP:
+		return 2;
+	case DP_PCON_DSC_ONE_BPP:
+		return 1;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_dsc_bpp_incr);
+
+static
+int drm_dp_pcon_configure_dsc_enc(struct drm_dp_aux *aux, u8 pps_buf_config)
+{
+	u8 buf;
+	int ret;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, &buf);
+	if (ret < 0)
+		return ret;
+
+	buf |= DP_PCON_ENABLE_DSC_ENCODER;
+
+	if (pps_buf_config <= DP_PCON_ENC_PPS_OVERRIDE_EN_BUFFER) {
+		buf &= ~DP_PCON_ENCODER_PPS_OVERRIDE_MASK;
+		buf |= pps_buf_config << 2;
+	}
+
+	ret = drm_dp_dpcd_writeb(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, buf);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+/**
+ * drm_dp_pcon_pps_default() - Let PCON fill the default pps parameters
+ * for DSC1.2 between PCON & HDMI2.1 sink
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns 0 on success, else returns negative error code.
+ */
+int drm_dp_pcon_pps_default(struct drm_dp_aux *aux)
+{
+	int ret;
+
+	ret = drm_dp_pcon_configure_dsc_enc(aux, DP_PCON_ENC_PPS_OVERRIDE_DISABLED);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_pps_default);
+
+/**
+ * drm_dp_pcon_pps_override_buf() - Configure PPS encoder override buffer for
+ * HDMI sink
+ * @aux: DisplayPort AUX channel
+ * @pps_buf: 128 bytes to be written into PPS buffer for HDMI sink by PCON.
+ *
+ * Returns 0 on success, else returns negative error code.
+ */
+int drm_dp_pcon_pps_override_buf(struct drm_dp_aux *aux, u8 pps_buf[128])
+{
+	int ret;
+
+	ret = drm_dp_dpcd_write(aux, DP_PCON_HDMI_PPS_OVERRIDE_BASE, &pps_buf, 128);
+	if (ret < 0)
+		return ret;
+
+	ret = drm_dp_pcon_configure_dsc_enc(aux, DP_PCON_ENC_PPS_OVERRIDE_EN_BUFFER);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_pps_override_buf);
+
+/*
+ * drm_dp_pcon_pps_override_param() - Write PPS parameters to DSC encoder
+ * override registers
+ * @aux: DisplayPort AUX channel
+ * @pps_param: 3 Parameters (2 Bytes each) : Slice Width, Slice Height,
+ * bits_per_pixel.
+ *
+ * Returns 0 on success, else returns negative error code.
+ */
+int drm_dp_pcon_pps_override_param(struct drm_dp_aux *aux, u8 pps_param[6])
+{
+	int ret;
+
+	ret = drm_dp_dpcd_write(aux, DP_PCON_HDMI_PPS_OVRD_SLICE_HEIGHT, &pps_param[0], 2);
+	if (ret < 0)
+		return ret;
+	ret = drm_dp_dpcd_write(aux, DP_PCON_HDMI_PPS_OVRD_SLICE_WIDTH, &pps_param[2], 2);
+	if (ret < 0)
+		return ret;
+	ret = drm_dp_dpcd_write(aux, DP_PCON_HDMI_PPS_OVRD_BPP, &pps_param[4], 2);
+	if (ret < 0)
+		return ret;
+
+	ret = drm_dp_pcon_configure_dsc_enc(aux, DP_PCON_ENC_PPS_OVERRIDE_EN_BUFFER);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_pps_override_param);
+
+/*
+ * drm_dp_pcon_convert_rgb_to_ycbcr() - Configure the PCon to convert RGB to Ycbcr
+ * @aux: displayPort AUX channel
+ * @color_spc: Color-space/s for which conversion is to be enabled, 0 for disable.
+ *
+ * Returns 0 on success, else returns negative error code.
+ */
+int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc)
+{
+	int ret;
+	u8 buf;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, &buf);
+	if (ret < 0)
+		return ret;
+
+	if (color_spc & DP_CONVERSION_RGB_YCBCR_MASK)
+		buf |= (color_spc & DP_CONVERSION_RGB_YCBCR_MASK);
+	else
+		buf &= ~DP_CONVERSION_RGB_YCBCR_MASK;
+
+	ret = drm_dp_dpcd_writeb(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, buf);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_pcon_convert_rgb_to_ycbcr);