[PATCH v3 2/4] drm_dp_mst_topology: use correct AUX channel

[Sam McNally]

From: Hans Verkuil <hans.verkuil at cisco.com>

For adapters behind an MST hub use the correct AUX channel.

Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
[sammc at chromium.org: rebased, removing redundant changes]
Signed-off-by: Sam McNally <sammc at chromium.org>
---

(no changes since v1)

 drivers/gpu/drm/drm_dp_mst_topology.c | 36 +++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 15b6cc39a754..0d753201adbd 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2255,6 +2255,9 @@ drm_dp_mst_topology_unlink_port(struct drm_dp_mst_topology_mgr *mgr,
 	drm_dp_mst_topology_put_port(port);
 }
 
+static ssize_t
+drm_dp_mst_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg);
+
 static struct drm_dp_mst_port *
 drm_dp_mst_add_port(struct drm_device *dev,
 		    struct drm_dp_mst_topology_mgr *mgr,
@@ -2271,9 +2274,13 @@ drm_dp_mst_add_port(struct drm_device *dev,
 	port->port_num = port_number;
 	port->mgr = mgr;
 	port->aux.name = "DPMST";
+	mutex_init(&port->aux.hw_mutex);
+	mutex_init(&port->aux.cec.lock);
 	port->aux.dev = dev->dev;
 	port->aux.is_remote = true;
 
+	port->aux.transfer = drm_dp_mst_aux_transfer;
+
 	/* initialize the MST downstream port's AUX crc work queue */
 	drm_dp_remote_aux_init(&port->aux);
 
@@ -3503,6 +3510,35 @@ static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
 	return 0;
 }
 
+static ssize_t
+drm_dp_mst_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+	struct drm_dp_mst_port *port =
+		container_of(aux, struct drm_dp_mst_port, aux);
+	int ret;
+
+	switch (msg->request & ~DP_AUX_I2C_MOT) {
+	case DP_AUX_NATIVE_WRITE:
+	case DP_AUX_I2C_WRITE:
+	case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+		ret = drm_dp_send_dpcd_write(port->mgr, port, msg->address,
+					     msg->size, msg->buffer);
+		break;
+
+	case DP_AUX_NATIVE_READ:
+	case DP_AUX_I2C_READ:
+		ret = drm_dp_send_dpcd_read(port->mgr, port, msg->address,
+					    msg->size, msg->buffer);
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
 static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8  dp_link_count)
 {
 	if (dp_link_bw == 0 || dp_link_count == 0)
-- 
2.28.0.681.g6f77f65b4e-goog