This patch takes care of the race condition between the Function Wake
Device Notification and the auto-suspend timeout for this situation:
Roothub
| (U3)
hub A
| (U3)
hub B
| (U3)
device C
When device C signals a resume, the xHCI driver will set the wakeup_bits
for the roothub port that hub A is attached to. However, since USB 3.0
hubs do not set a link state change bit on device-initiated resume, hub
A will not indicate a port event when polled. Without this patch, khubd
will notice the wakeup-bits are set for the roothub port, it will resume
hub A, and then it will poll the events bits for hub A and notice that
nothing has changed. Then it will be suspended after 2 seconds.
Change hub_activate() to look at the port link state for each USB 3.0
hub port, and set hub->change_bits if the link state is U0, indicating
the device has finished resume. Change the resume function called by
hub_events(), hub_handle_remote_wakeup(), to check the link status
for resume instead of just the port's wakeup_bits.
Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
---
drivers/usb/core/hub.c | 22 +++++++++++++++-------
1 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 0e5f78c..5a158fe 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -853,12 +853,19 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
set_bit(port1, hub->change_bits);
} else if (portstatus & USB_PORT_STAT_ENABLE) {
+ bool port_resumed = (portstatus &
+ USB_PORT_STAT_LINK_STATE) ==
+ USB_SS_PORT_LS_U0;
/* The power session apparently survived the resume.
* If there was an overcurrent or suspend change
* (i.e., remote wakeup request), have khubd
- * take care of it.
+ * take care of it. Look at the port link state
+ * for USB 3.0 hubs, since they don't have a suspend
+ * change bit, and they don't set the port link change
+ * bit on device-initiated resume.
*/
- if (portchange)
+ if (portchange || (hub_is_superspeed(hub->hdev) &&
+ port_resumed))
set_bit(port1, hub->change_bits);
} else if (udev->persist_enabled) {
@@ -3469,7 +3476,7 @@ done:
/* Returns 1 if there was a remote wakeup and a connect status change. */
static int hub_handle_remote_wakeup(struct usb_hub *hub, unsigned int port,
- u16 portchange)
+ u16 portstatus, u16 portchange)
{
struct usb_device *hdev;
struct usb_device *udev;
@@ -3484,8 +3491,8 @@ static int hub_handle_remote_wakeup(struct usb_hub *hub, unsigned int port,
clear_port_feature(hdev, port, USB_PORT_FEAT_C_SUSPEND);
} else {
if (!udev || udev->state != USB_STATE_SUSPENDED ||
- !test_and_clear_bit(udev->portnum,
- hub->wakeup_bits))
+ (portstatus & USB_PORT_STAT_LINK_STATE) !=
+ USB_SS_PORT_LS_U0)
return 0;
}
@@ -3598,7 +3605,7 @@ static void hub_events(void)
if (test_bit(i, hub->busy_bits))
continue;
connect_change = test_bit(i, hub->change_bits);
- wakeup_change = test_bit(i, hub->wakeup_bits);
+ wakeup_change = test_and_clear_bit(i, hub->wakeup_bits);
if (!test_and_clear_bit(i, hub->event_bits) &&
!connect_change && !wakeup_change)
continue;
@@ -3641,7 +3648,8 @@ static void hub_events(void)
}
}
- if (hub_handle_remote_wakeup(hub, i, portchange))
+ if (hub_handle_remote_wakeup(hub, i,
+ portstatus, portchange))
connect_change = 1;
if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
--
1.7.5.4
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