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.
v2: As suggested in review comments:
-Fixed bug in the check condition in a drm_helper as reported by
Dan Carpenter and Kernel test robot. (Dan Carepenter)
-Modified the color-conversion cap helper function, to accomodate
BT709 and BT2020 colorspace. (Uma Shankar)
-Added spec details for the new cap for color conversion. (Uma Shankar)
Signed-off-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>
---
drivers/gpu/drm/drm_dp_helper.c | 61 +++++++++++++++++++++++++++++++++
include/drm/drm_dp_helper.h | 19 +++++++++-
2 files changed, 79 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 689fd0d5f6c5..9abd65c694ab 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -949,6 +949,38 @@ 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
@@ -3101,3 +3133,32 @@ 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/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);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index baad87fe6b0a..e096ee98842b 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -432,6 +432,17 @@ struct drm_device;
# define DP_DS_HDMI_YCBCR444_TO_422_CONV (1 << 3)
# define DP_DS_HDMI_YCBCR444_TO_420_CONV (1 << 4)
+/*
+ * VESA DP-to-HDMI PCON Specification adds caps for colorspace
+ * conversion in DFP cap DPCD 83h. Sec6.1 Table-3.
+ * Based on the available support the source can enable
+ * color conversion by writing into PROTOCOL_COVERTER_CONTROL_2
+ * DPCD 3052h.
+ */
+# 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
/* DP Forward error Correction Registers */
@@ -1207,7 +1218,10 @@ 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_RGB_YCBCR_MASK (7 << 4)
+# 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
@@ -2167,5 +2181,8 @@ 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], u8
color_spc);
+int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc);
#endif /* _DRM_DP_HELPER_H_ */
--
2.17.1
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