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 <stern@xxxxxxxxxxxxxxxxxxx>
[alan]: add a 'superspeed' flag to the port
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/usb/core/hub.c | 22 +++-----------
drivers/usb/core/hub.h | 15 ++++++++++
drivers/usb/core/port.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 93 insertions(+), 17 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 3d50f82faea9..2269f54da0a9 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -36,11 +36,6 @@
#define USB_VENDOR_GENESYS_LOGIC 0x05e3
#define HUB_QUIRK_CHECK_PORT_AUTOSUSPEND 0x01
-static inline int hub_is_superspeed(struct usb_device *hdev)
-{
- return (hdev->descriptor.bDeviceProtocol == USB_HUB_PR_SS);
-}
-
/* Protect struct usb_device->state and ->children members
* Note: Both are also protected by ->dev.sem, except that ->state can
* change to USB_STATE_NOTATTACHED even when the semaphore isn't held. */
@@ -822,14 +817,9 @@ int usb_hub_clear_tt_buffer(struct urb *urb)
}
EXPORT_SYMBOL_GPL(usb_hub_clear_tt_buffer);
-/* If do_delay is false, return the number of milliseconds the caller
- * needs to delay.
- */
-static unsigned hub_power_on(struct usb_hub *hub, bool do_delay)
+static void hub_power_on(struct usb_hub *hub, bool do_delay)
{
int port1;
- unsigned pgood_delay = hub->descriptor->bPwrOn2PwrGood * 2;
- unsigned delay;
/* Enable power on each port. Some hubs have reserved values
* of LPSM (> 2) in their descriptors, even though they are
@@ -848,12 +838,8 @@ static unsigned hub_power_on(struct usb_hub *hub, bool do_delay)
else
usb_clear_port_feature(hub->hdev, port1,
USB_PORT_FEAT_POWER);
-
- /* Wait at least 100 msec for power to become stable */
- delay = max(pgood_delay, (unsigned) 100);
if (do_delay)
- msleep(delay);
- return delay;
+ msleep(hub_power_on_good_delay(hub));
}
static int hub_hub_status(struct usb_hub *hub,
@@ -1057,7 +1043,9 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
* for HUB_POST_RESET, but it's easier not to.
*/
if (type == HUB_INIT) {
- delay = hub_power_on(hub, false);
+ unsigned delay = hub_power_on_good_delay(hub);
+
+ hub_power_on(hub, false);
INIT_DELAYED_WORK(&hub->init_work, hub_init_func2);
queue_delayed_work(system_power_efficient_wq,
&hub->init_work,
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 3ef1c2e435cc..906c355e0631 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -89,6 +89,7 @@ struct usb_hub {
* @connect_type: port's connect type
* @location: opaque representation of platform connector location
* @portnum: port index num based one
+ * @is_superspeed cache super-speed status
*/
struct usb_port {
struct usb_device *child;
@@ -98,6 +99,7 @@ struct usb_port {
enum usb_port_connect_type connect_type;
usb_port_location_t location;
u8 portnum;
+ unsigned int is_superspeed:1;
};
#define to_usb_port(_dev) \
@@ -125,6 +127,19 @@ static inline bool hub_is_port_power_switchable(struct usb_hub *hub)
return (le16_to_cpu(hcs) & HUB_CHAR_LPSM) < HUB_CHAR_NO_LPSM;
}
+static inline int hub_is_superspeed(struct usb_device *hdev)
+{
+ return hdev->descriptor.bDeviceProtocol == USB_HUB_PR_SS;
+}
+
+static inline unsigned hub_power_on_good_delay(struct usb_hub *hub)
+{
+ unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2;
+
+ /* Wait at least 100 msec for power to become stable */
+ return max(delay, 100U);
+}
+
static inline int hub_port_debounce_be_connected(struct usb_hub *hub,
int port1)
{
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);
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
