thunderbolt: Add Display Port CM handshake for Titan Ridge devices
Titan Ridge needs an additional connection manager handshake in order to
do proper Display Port tunneling so implement it here.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c
index 3353396..009c268 100644
--- a/drivers/thunderbolt/tunnel.c
+++ b/drivers/thunderbolt/tunnel.c
@@ -6,6 +6,7 @@
* Copyright (C) 2019, Intel Corporation
*/
+#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/list.h>
@@ -242,6 +243,42 @@ struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
return tunnel;
}
+static int tb_dp_cm_handshake(struct tb_port *in, struct tb_port *out)
+{
+ int timeout = 10;
+ u32 val;
+ int ret;
+
+ /* Both ends need to support this */
+ if (!tb_switch_is_titan_ridge(in->sw) ||
+ !tb_switch_is_titan_ridge(out->sw))
+ return 0;
+
+ ret = tb_port_read(out, &val, TB_CFG_PORT,
+ out->cap_adap + DP_STATUS_CTRL, 1);
+ if (ret)
+ return ret;
+
+ val |= DP_STATUS_CTRL_UF | DP_STATUS_CTRL_CMHS;
+
+ ret = tb_port_write(out, &val, TB_CFG_PORT,
+ out->cap_adap + DP_STATUS_CTRL, 1);
+ if (ret)
+ return ret;
+
+ do {
+ ret = tb_port_read(out, &val, TB_CFG_PORT,
+ out->cap_adap + DP_STATUS_CTRL, 1);
+ if (ret)
+ return ret;
+ if (!(val & DP_STATUS_CTRL_CMHS))
+ return 0;
+ usleep_range(10, 100);
+ } while (timeout--);
+
+ return -ETIMEDOUT;
+}
+
static int tb_dp_xchg_caps(struct tb_tunnel *tunnel)
{
struct tb_port *out = tunnel->dst_port;
@@ -256,6 +293,14 @@ static int tb_dp_xchg_caps(struct tb_tunnel *tunnel)
if (in->sw->generation < 2 || out->sw->generation < 2)
return 0;
+ /*
+ * Perform connection manager handshake between IN and OUT ports
+ * before capabilities exchange can take place.
+ */
+ ret = tb_dp_cm_handshake(in, out);
+ if (ret)
+ return ret;
+
/* Read both DP_LOCAL_CAP registers */
ret = tb_port_read(in, &in_dp_cap, TB_CFG_PORT,
in->cap_adap + DP_LOCAL_CAP, 1);