[PATCH v4 07/16] drm/dp_helper: Add helpers to configure PCONs RGB-YCbCr Conversion

[Ankit Nautiyal]

DP Specification for DP2.0 to HDMI2.1 Pcon specifies support for conversion
of colorspace from RGB to YCbCr.
https://groups.vesa.org/wg/DP/document/previewpdf/15651

This patch adds the relavant registers and helper functions to
get the capability and set the color conversion bits for rgb->ycbcr
conversion through PCON.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 59 +++++++++++++++++++++++++++++++++
 include/drm/drm_dp_helper.h     | 10 +++++-
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index d0626f57f99c..344662d5c295 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -949,6 +949,35 @@ 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
+ *
+ * Returns: whether the downstream facing port can convert RGB->YCbCr
+ */
+bool drm_dp_downstream_rgb_to_ycbcr_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_BT601_RGB_YCBCR_CONV;
+	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
@@ -3140,3 +3169,33 @@ int drm_dp_pcon_pps_override_param(struct drm_dp_aux *aux, u8 pps_param[6])
 	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 conversion type
+ *
+ * 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;
+
+	if (color_spc != DP_CONVERSION_BT601_RGB_YCBCR_ENABLE ||
+	    color_spc != DP_CONVERSION_BT709_RGB_YCBCR_ENABLE ||
+	    color_spc != DP_CONVERSION_BT2020_RGB_YCBCR_ENABLE)
+		return -EINVAL;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PROTOCOL_CONVERTER_CONTROL_2, &buf);
+	if (ret < 0)
+		return ret;
+
+	buf |= color_spc;
+	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);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 347b4e1a55b4..1b3d54ed7a78 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -431,6 +431,9 @@ struct drm_device;
 # define DP_DS_HDMI_YCBCR420_PASS_THROUGH   (1 << 2)
 # define DP_DS_HDMI_YCBCR444_TO_422_CONV    (1 << 3)
 # define DP_DS_HDMI_YCBCR444_TO_420_CONV    (1 << 4)
+# define DP_DS_HDMI_BT601_RGB_YCBCR_CONV    (1 << 5)
+# define DP_DS_HDMI_BT709_RGB_YCBCR_CONV    (1 << 6)
+# define DP_DS_HDMI_BT2020_RGB_YCBCR_CONV   (1 << 7)
 
 #define DP_MAX_DOWNSTREAM_PORTS		    0x10
 
@@ -1217,7 +1220,9 @@ struct drm_device;
 # define DP_PCON_ENC_PPS_OVERRIDE_DISABLED      0
 # define DP_PCON_ENC_PPS_OVERRIDE_EN_PARAMS     1
 # define DP_PCON_ENC_PPS_OVERRIDE_EN_BUFFER     2
-
+# define DP_CONVERSION_BT601_RGB_YCBCR_ENABLE  (1 << 4)
+# define DP_CONVERSION_BT709_RGB_YCBCR_ENABLE  (1 << 5)
+# define DP_CONVERSION_BT2020_RGB_YCBCR_ENABLE (1 << 6)
 
 /* PCON Downstream HDMI ERROR Status per Lane */
 #define DP_PCON_HDMI_ERROR_STATUS_LN0          0x3037
@@ -2178,5 +2183,8 @@ int drm_dp_pcon_dsc_bpp_incr(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE
 int drm_dp_pcon_pps_default(struct drm_dp_aux *aux);
 int drm_dp_pcon_pps_override_buf(struct drm_dp_aux *aux, u8 pps_buf[128]);
 int drm_dp_pcon_pps_override_param(struct drm_dp_aux *aux, u8 pps_param[6]);
+bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+					       const u8 port_cap[4]);
+int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc);
 
 #endif /* _DRM_DP_HELPER_H_ */
-- 
2.17.1