[PATCH v15 1/9] drm/dp: Add support to indicate if sink supports AS SDP

[Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx>]

Add an API that indicates support for Adaptive Sync SDP in
the sink, which can be utilized by the rest of the DP programming.

--v1:
- Format commit message properly.

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 25 +++++++++++++++++++++++++
 include/drm/display/drm_dp_helper.h     |  1 +
 2 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 266826eac4a7..f2fabb673aa4 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -2948,6 +2948,31 @@ void drm_dp_vsc_sdp_log(struct drm_printer *p, const struct drm_dp_vsc_sdp *vsc)
 }
 EXPORT_SYMBOL(drm_dp_vsc_sdp_log);
 
+/**
+ * drm_dp_as_sdp_supported() - check if adaptive sync sdp is supported
+ * @aux: DisplayPort AUX channel
+ * @dpcd: DisplayPort configuration data
+ *
+ * Returns true if adaptive sync sdp is supported, else returns false
+ */
+bool drm_dp_as_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 rx_feature;
+
+	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_13)
+		return false;
+
+	if (drm_dp_dpcd_readb(aux, DP_DPRX_FEATURE_ENUMERATION_LIST_CONT_1,
+			      &rx_feature) != 1) {
+		drm_dbg_dp(aux->drm_dev,
+			   "Failed to read DP_DPRX_FEATURE_ENUMERATION_LIST_CONT_1\n");
+		return false;
+	}
+
+	return (rx_feature & DP_ADAPTIVE_SYNC_SDP_SUPPORTED);
+}
+EXPORT_SYMBOL(drm_dp_as_sdp_supported);
+
 /**
  * drm_dp_vsc_sdp_supported() - check if vsc sdp is supported
  * @aux: DisplayPort AUX channel
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index a62fcd051d4d..7df19acdc790 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -101,6 +101,7 @@ struct drm_dp_vsc_sdp {
 void drm_dp_vsc_sdp_log(struct drm_printer *p, 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]);
+bool drm_dp_as_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]);
 
-- 
2.25.1