From 7ad3c47088f9faec463f5226e5e968a5c3b0e593 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 20 May 2014 18:08:57 -0700 Subject: usb: block suspension of superspeed port while hispeed peer is active 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. By default the latency between peer power-on events is 0. In order for the device to not see usb2 active while usb3 is still powering up inject the hub recommended power_on_good delay. In support of satisfying the power_on_good delay outside of hub_power_on() refactor the places where the delay is consumed to call a new hub_power_on_good_delay() helper. Finally, because this introduces several new checks for whether a port is_superspeed, cache that disctinction at port creation so that we don't need to keep looking up the parent hub device. Acked-by: Alan Stern [alan]: add a 'superspeed' flag to the port Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/port.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) (limited to 'drivers/usb/core/port.c') diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c index 795778c71e31..827b0d38f73d 100644 --- a/drivers/usb/core/port.c +++ b/drivers/usb/core/port.c @@ -76,6 +76,7 @@ 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; @@ -86,10 +87,18 @@ static int usb_port_runtime_resume(struct device *dev) return 0; } + /* + * Power on our usb3 peer before this usb2 port to prevent a usb3 + * device from degrading to its usb2 connection + */ + if (!port_dev->is_superspeed && peer) + pm_runtime_get_sync(&peer->dev); + usb_autopm_get_interface(intf); set_bit(port1, hub->busy_bits); retval = usb_hub_set_port_power(hdev, hub, port1, true); + msleep(hub_power_on_good_delay(hub)); if (port_dev->child && !retval) { /* * Attempt to wait for usb hub port to be reconnected in order @@ -107,6 +116,7 @@ static int usb_port_runtime_resume(struct device *dev) clear_bit(port1, hub->busy_bits); usb_autopm_put_interface(intf); + return retval; } @@ -116,6 +126,7 @@ 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; @@ -135,6 +146,15 @@ 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, so + * asynchronously queue a suspend request to observe that this + * usb2 port is now off. + */ + if (!port_dev->is_superspeed && peer) + pm_runtime_put(&peer->dev); + return retval; } #endif @@ -159,6 +179,7 @@ static struct device_driver usb_port_driver = { static int link_peers(struct usb_port *left, struct usb_port *right) { + struct usb_port *ss_port, *hs_port; int rc; if (left->peer == right && right->peer == left) @@ -184,9 +205,36 @@ static int link_peers(struct usb_port *left, struct usb_port *right) return rc; } + /* + * We need to wake the HiSpeed port to make sure we don't race + * setting ->peer with usb_port_runtime_suspend(). Otherwise we + * may miss a suspend event for the SuperSpeed port. + */ + if (left->is_superspeed) { + ss_port = left; + WARN_ON(right->is_superspeed); + hs_port = right; + } else { + ss_port = right; + WARN_ON(!right->is_superspeed); + hs_port = left; + } + pm_runtime_get_sync(&hs_port->dev); + left->peer = right; right->peer = left; + /* + * The SuperSpeed reference is dropped when the HiSpeed port in + * this relationship suspends, i.e. when it is safe to allow a + * SuperSpeed connection to drop since there is no risk of a + * device degrading to its powered-off HiSpeed connection. + * + * Also, drop the HiSpeed ref taken above. + */ + pm_runtime_get_sync(&ss_port->dev); + pm_runtime_put(&hs_port->dev); + return 0; } @@ -206,14 +254,37 @@ static void link_peers_report(struct usb_port *left, struct usb_port *right) static void unlink_peers(struct usb_port *left, struct usb_port *right) { + struct usb_port *ss_port, *hs_port; + WARN(right->peer != left || left->peer != right, "%s and %s are not peers?\n", dev_name(&left->dev), dev_name(&right->dev)); + /* + * We wake the HiSpeed port to make sure we don't race its + * usb_port_runtime_resume() event which takes a SuperSpeed ref + * when ->peer is !NULL. + */ + if (left->is_superspeed) { + ss_port = left; + hs_port = right; + } else { + ss_port = right; + hs_port = left; + } + + pm_runtime_get_sync(&hs_port->dev); + sysfs_remove_link(&left->dev.kobj, "peer"); right->peer = NULL; sysfs_remove_link(&right->dev.kobj, "peer"); left->peer = NULL; + + /* Drop the SuperSpeed ref held on behalf of the active HiSpeed port */ + pm_runtime_put(&ss_port->dev); + + /* Drop the ref taken above */ + pm_runtime_put(&hs_port->dev); } /* @@ -325,6 +396,8 @@ int usb_hub_create_port_device(struct usb_hub *hub, int port1) port_dev->dev.groups = port_dev_group; port_dev->dev.type = &usb_port_device_type; port_dev->dev.driver = &usb_port_driver; + if (hub_is_superspeed(hub->hdev)) + port_dev->is_superspeed = 1; dev_set_name(&port_dev->dev, "%s-port%d", dev_name(&hub->hdev->dev), port1); retval = device_register(&port_dev->dev); -- cgit