drm: Read DP branch device id

Read DisplayPort branch device id string.

Reviewed-by: Jim Bride <jim.bride@linux.intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1473419458-17080-6-git-send-email-mika.kahola@intel.com

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 57c61d1..7b3a638 100644 (file)
--- 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 f3d1424..faea76b 100644 (file)
--- 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
@@ -819,6 +820,7 @@ 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]);
 
 void drm_dp_aux_init(struct drm_dp_aux *aux);
 int drm_dp_aux_register(struct drm_dp_aux *aux);