[PATCH v3] drm/dp: add an API to indicate if sink supports VSC SDP

[Abhinav Kumar]

From: Paloma Arellano <quic_parellan@xxxxxxxxxxx>

YUV420 format is supported only in the VSC SDP packet and not through
MSA. Hence add an API which indicates the sink support which can be used
by the rest of the DP programming.

changes in v3:
	- fix the commit title prefix to drm/dp
	- get rid of redundant !!
	- break out this change from series [1] to get acks from drm core
	  maintainers

Changes in v2:
	- Move VSC SDP support check API from dp_panel.c to
	  drm_dp_helper.c

[1]: https://patchwork.freedesktop.org/series/129180/

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Signed-off-by: Paloma Arellano <quic_parellan@xxxxxxxxxxx>
Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 21 +++++++++++++++++++++
 include/drm/display/drm_dp_helper.h     |  1 +
 2 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index b1ca3a1100da..7a851f92b249 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -2916,6 +2916,27 @@ void drm_dp_vsc_sdp_log(const char *level, struct device *dev,
 }
 EXPORT_SYMBOL(drm_dp_vsc_sdp_log);
 
+/**
+ * drm_dp_vsc_sdp_supported() - check if vsc sdp is supported
+ * @aux: DisplayPort AUX channel
+ * @dpcd: DisplayPort configuration data
+ *
+ * Returns true if vsc sdp is supported, else returns false
+ */
+bool drm_dp_vsc_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 rx_feature;
+
+	if (drm_dp_dpcd_readb(aux, DP_DPRX_FEATURE_ENUMERATION_LIST, &rx_feature) != 1) {
+		drm_dbg_dp(aux->drm_dev, "failed to read DP_DPRX_FEATURE_ENUMERATION_LIST\n");
+		return false;
+	}
+
+	return (dpcd[DP_DPCD_REV] >= DP_DPCD_REV_13) &&
+		(rx_feature & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED);
+}
+EXPORT_SYMBOL(drm_dp_vsc_sdp_supported);
+
 /**
  * drm_dp_get_pcon_max_frl_bw() - maximum frl supported by PCON
  * @dpcd: DisplayPort configuration data
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index 863b2e7add29..948381b2b0b1 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -100,6 +100,7 @@ struct drm_dp_vsc_sdp {
 
 void drm_dp_vsc_sdp_log(const char *level, struct device *dev,
 			const struct drm_dp_vsc_sdp *vsc);
+bool drm_dp_vsc_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
 
 int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE]);
 
-- 
2.34.1