ClearPortFeature(PORT_POWER) on a usb3 port places the port in either a
DSPORT.Powered-off-detect / DSPORT.Powered-off-reset loop, or the
DSPORT.Powered-off state. There is no way to ensure that RX
terminations will persist in this state, so it is possible a device will
degrade to its usb2 connection. Prevent this by blocking power-off of a
usb3 port while its usb2 peer is active, and powering on a usb3 port
before its usb2 peer.
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/usb/core/port.c | 36 ++++++++++++++++++++++++++++++++++++
1 files changed, 36 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index d3aacf093aa1..2227379be652 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -77,12 +77,19 @@ static int usb_port_runtime_resume(struct device *dev)
struct usb_device *hdev = to_usb_device(dev->parent->parent);
struct usb_interface *intf = to_usb_interface(dev->parent);
struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
+ struct usb_port *peer = port_dev->peer;
int port1 = port_dev->portnum;
int retval;
if (!hub)
return -EINVAL;
+ /* power on our usb3 peer before this usb2 port to prevent a usb3
+ * device from degrading to its usb2 connection
+ */
+ if (!hub_is_superspeed(hdev) && peer)
+ pm_runtime_get_sync(&peer->dev);
+
usb_autopm_get_interface(intf);
set_bit(port1, hub->busy_bits);
@@ -104,6 +111,13 @@ static int usb_port_runtime_resume(struct device *dev)
clear_bit(port1, hub->busy_bits);
usb_autopm_put_interface(intf);
+
+ /* usb3 peer is marked active so we can drop the reference we took to
+ * ensure ordering above
+ */
+ if (!hub_is_superspeed(hdev) && peer)
+ pm_runtime_put(&peer->dev);
+
return retval;
}
@@ -113,6 +127,7 @@ static int usb_port_runtime_suspend(struct device *dev)
struct usb_device *hdev = to_usb_device(dev->parent->parent);
struct usb_interface *intf = to_usb_interface(dev->parent);
struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
+ struct usb_port *peer = port_dev->peer;
int port1 = port_dev->portnum;
int retval;
@@ -123,6 +138,16 @@ static int usb_port_runtime_suspend(struct device *dev)
== PM_QOS_FLAGS_ALL)
return -EAGAIN;
+ /* block poweroff of superspeed ports while highspeed peer is on */
+ dev_WARN_ONCE(&hdev->dev, hub_is_superspeed(hdev) && !peer,
+ "port%d missing peer info\n", port1);
+
+ /* prevent a usb3 port from powering off while its usb2 peer is
+ * powered on
+ */
+ if (hub_is_superspeed(hdev) && (!peer || peer->power_is_on))
+ return -EBUSY;
+
usb_autopm_get_interface(intf);
set_bit(port1, hub->busy_bits);
retval = usb_hub_set_port_power(hdev, hub, port1, false);
@@ -130,6 +155,17 @@ static int usb_port_runtime_suspend(struct device *dev)
usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_ENABLE);
clear_bit(port1, hub->busy_bits);
usb_autopm_put_interface(intf);
+
+ /* Our peer usb3 port may now be able to suspend, asynchronously
+ * queue a suspend request to observe that this usb2 peer port
+ * is now off. There is a small race since there is no way to
+ * flush this suspend, userspace is advised to order suspends.
+ */
+ if (!hub_is_superspeed(hdev) && peer) {
+ pm_runtime_get(&peer->dev);
+ pm_runtime_put(&peer->dev);
+ }
+
return retval;
}
#endif
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