Merge "drm/dp: complete the implementation for remote dpcd read" into dev/msm-4.14-display

#if 0 /* unused as of yet */

static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,

				 struct drm_dp_mst_port *port,

				 int offset, int size)

				 int offset, int size, u8 *bytes)

{

	int len;

	int ret;

	struct drm_dp_sideband_msg_tx *txmsg;

	struct drm_dp_mst_branch *mstb;

	memset(bytes, 0, size);

	mstb = drm_dp_get_validated_mstb_ref(mgr, port->parent);

	if (!mstb)

		return -EINVAL;

	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);

	if (!txmsg)

		return -ENOMEM;

	if (!txmsg) {

		ret = -ENOMEM;

		goto fail_put;

	}

	len = build_dpcd_read(txmsg, port->port_num, 0, 8);

	txmsg->dst = port->parent;

	len = build_dpcd_read(txmsg, port->port_num, offset, size);

	txmsg->dst = mstb;

	drm_dp_queue_down_tx(mgr, txmsg);

	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);

	if (ret <= 0) {

		DRM_ERROR("dpcd read failed\n");

		goto fail_free_msg;

	}

	return 0;

	if (txmsg->reply.reply_type == 1) {

		DRM_ERROR("dpcd read nack received\n");

		ret = -EINVAL;

		goto fail_free_msg;

	}

	if (port->port_num != txmsg->reply.u.remote_dpcd_read_ack.port_number) {

		DRM_ERROR("got incorrect port in response\n");

		ret = -EINVAL;

		goto fail_free_msg;

	}

	if (size > txmsg->reply.u.remote_dpcd_read_ack.num_bytes)

		size = txmsg->reply.u.remote_dpcd_read_ack.num_bytes;

	memcpy(bytes, txmsg->reply.u.remote_dpcd_read_ack.bytes, size);

fail_free_msg:

	kfree(txmsg);

fail_put:

	drm_dp_put_mst_branch_device(mstb);

	return ret;

}

#endif