[PATCH 1/2] thunderbolt: Handle bandwidth allocation mode enablement notification

[Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>]

When the graphics side enables bandwidth allocation mode the DP IN
adapter sends notification to the connection manager about this.
Currently the handler misses this and tries to allocate 0 Mb/s that then
makes the graphics side to think the request failed.

Fix this by properly handling the enablement notification.

Fixes: 6ce3563520be ("thunderbolt: Add support for DisplayPort bandwidth allocation mode")
Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
---
 drivers/thunderbolt/tb.c   | 10 +++++++---
 drivers/thunderbolt/usb4.c |  7 ++++---
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 0b891d749a96..7bfbc9ca9ba4 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -1756,11 +1756,15 @@ static void tb_handle_dp_bandwidth_request(struct work_struct *work)
 		goto unlock;
 	}
 
-	requested_bw = usb4_dp_port_requested_bw(in);
-	if (requested_bw < 0) {
-		tb_port_dbg(in, "no bandwidth request active\n");
+	ret = usb4_dp_port_requested_bw(in);
+	if (ret < 0) {
+		if (ret == -ENODATA)
+			tb_port_dbg(in, "no bandwidth request active\n");
+		else
+			tb_port_warn(in, "failed to read requested bandwidth\n");
 		goto unlock;
 	}
+	requested_bw = ret;
 
 	tb_port_dbg(in, "requested bandwidth %d Mb/s\n", requested_bw);
 
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index 2a9266fb5c0f..1e5e9c147a31 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -2732,7 +2732,8 @@ int usb4_dp_port_allocate_bw(struct tb_port *port, int bw)
  * Reads the DPCD (graphics driver) requested bandwidth and returns it
  * in Mb/s. Takes the programmed granularity into account. In case of
  * error returns negative errno. Specifically returns %-EOPNOTSUPP if
- * the adapter does not support bandwidth allocation mode.
+ * the adapter does not support bandwidth allocation mode, and %ENODATA
+ * if there is no active bandwidth request from the graphics driver.
  */
 int usb4_dp_port_requested_bw(struct tb_port *port)
 {
@@ -2750,10 +2751,10 @@ int usb4_dp_port_requested_bw(struct tb_port *port)
 	ret = tb_port_read(port, &val, TB_CFG_PORT,
 			   port->cap_adap + ADP_DP_CS_8, 1);
 	if (ret)
-		return 0;
+		return ret;
 
 	if (!(val & ADP_DP_CS_8_DR))
-		return 0;
+		return -ENODATA;
 
 	return (val & ADP_DP_CS_8_REQUESTED_BW_MASK) * granularity;
 }
-- 
2.39.0