Read DisplayPort branch device id string.
Signed-off-by: Mika Kahola <mika.kahola@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_helper.c | 12 ++++++++++++
include/drm/drm_dp_helper.h | 2 ++
2 files changed, 14 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 3dab8a4..0c83685 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -513,6 +513,18 @@ int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
}
EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
+/**
+ * drm_dp_downstream_id() - identify branch device
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns branch device id on success or NULL on failure
+ */
+int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6])
+{
+ return drm_dp_dpcd_read(aux, DP_BRANCH_ID, id, 6);
+}
+EXPORT_SYMBOL(drm_dp_downstream_id);
+
/*
* I2C-over-AUX implementation
*/
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index b18d17c..88bf3bf 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -445,6 +445,7 @@
#define DP_SOURCE_OUI 0x300
#define DP_SINK_OUI 0x400
#define DP_BRANCH_OUI 0x500
+#define DP_BRANCH_ID 0x503
#define DP_SET_POWER 0x600
# define DP_SET_POWER_D0 0x1
@@ -810,6 +811,7 @@ int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4]);
int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4]);
+int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
int drm_dp_aux_register(struct drm_dp_aux *aux);
void drm_dp_aux_unregister(struct drm_dp_aux *aux);
--
1.9.1
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