When DP downstream has HDMI branch, it checks below functionality and
shows supports. It follows DP 1.4a spec; Table 2-161: Address Mapping
within DPCD Receiver Capability Field (DPCD Addresses 00000h
through 000FFh).
Added flags for DP downstream:
YCBCR422_PASS_THROUGH_SUPPORT, YCBCR420_PASS_THROUGH_SUPPORT,
CONVERSION_FROM_YCBCR444_TO_YCBCR422_SUPPORT and
CONVERSION_FROM_YCBCR444_TO_YCBCR420_SUPPORT.
Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_helper.c | 19 +++++++++++++++++++
include/drm/drm_dp_helper.h | 5 +++++
2 files changed, 24 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 5a103e9b3c86..cb6dcfb13127 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -531,6 +531,25 @@ void drm_dp_downstream_debug(struct seq_file *m,
if (bpc > 0)
seq_printf(m, "\t\tMax bpc: %d\n", bpc);
+
+ if (type == DP_DS_PORT_TYPE_HDMI) {
+ bool ycbcr422_passthru = port_cap[3] &
+ DP_DS_YCBCR422_PASSTHRU_SUPPORT;
+ bool ycbcr420_passthru = port_cap[3] &
+ DP_DS_YCBCR420_PASSTHRU_SUPPORT;
+ bool ycbcr422_convert = port_cap[3] &
+ DP_DS_CONV_YCBCR444_TO_YCBCR422_SUPPORT;
+ bool ycbcr420_convert = port_cap[3] &
+ DP_DS_CONV_YCBCR444_TO_YCBCR420_SUPPORT;
+ seq_printf(m, "\t\tHDMI YCbCr 4:2:2 pass-through support: %s\n",
+ ycbcr422_passthru ? "yes" : "no");
+ seq_printf(m, "\t\tHDMI YCbCr 4:2:0 pass-through support: %s\n",
+ ycbcr420_passthru ? "yes" : "no");
+ seq_printf(m, "\t\tHDMI YCbCr 4:4:4 to YCbCr 4:2:2 Convert support: %s\n",
+ ycbcr422_convert ? "yes" : "no");
+ seq_printf(m, "\t\tHDMI YCbCr 4:4:4 to YCbCr 4:2:0 Convert support: %s\n",
+ ycbcr420_convert ? "yes" : "no");
+ }
}
}
EXPORT_SYMBOL(drm_dp_downstream_debug);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 262faf9e5e94..d61eadaba769 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -391,6 +391,11 @@
# define DP_DS_10BPC 1
# define DP_DS_12BPC 2
# define DP_DS_16BPC 3
+/* offset 3 for HDMI */
+# define DP_DS_YCBCR422_PASSTHRU_SUPPORT (1 << 1) /* 1.4 */
+# define DP_DS_YCBCR420_PASSTHRU_SUPPORT (1 << 2)
+# define DP_DS_CONV_YCBCR444_TO_YCBCR422_SUPPORT (1 << 3)
+# define DP_DS_CONV_YCBCR444_TO_YCBCR420_SUPPORT (1 << 4)
#define DP_MAX_DOWNSTREAM_PORTS 0x10
--
2.24.1
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