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authorAlan Stern <stern@rowland.harvard.edu>2008-03-03 15:15:36 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2008-04-24 21:16:32 -0700
commit3bb1af5243d41af9518728445e9c9bd30dd47237 (patch)
tree83a82f0bb1ca4ab268b49a9d1e06548bb33e52ef /drivers/usb/core
parent8f7f85e9f9561507b009d26395c53e70758695ec (diff)
USB: EHCI: carry out port handover during each root-hub resume
This patch (as1044) causes EHCI port handover for non-high-speed devices to occur during every root-hub resume, not just in cases where the controller lost power or was reset. This is necessary because: When some machines go into suspend, they remove power from on-board USB devices while retaining suspend current for USB controllers. The user might well unplug a USB device while the system is suspended and then plug it back in before resuming. A corresponding change is made to the core resume routine; now high-speed root hubs will always be resumed when the system wakes up, even if they were suspended before the system went to sleep. If this weren't done then EHCI port handover wouldn't work, since it is called when the EHCI root hub is resumed. Finally, a comment is added to the hub driver explaining the khubd has to be freezable; if it weren't frozen then it could interfere with port handover. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/core')
-rw-r--r--drivers/usb/core/driver.c9
-rw-r--r--drivers/usb/core/hub.c6
2 files changed, 13 insertions, 2 deletions
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 801b6f142fa..ebccdefcc6f 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1523,9 +1523,14 @@ static int usb_suspend(struct device *dev, pm_message_t message)
udev = to_usb_device(dev);
/* If udev is already suspended, we can skip this suspend and
- * we should also skip the upcoming system resume. */
+ * we should also skip the upcoming system resume. High-speed
+ * root hubs are an exception; they need to resume whenever the
+ * system wakes up in order for USB-PERSIST port handover to work
+ * properly.
+ */
if (udev->state == USB_STATE_SUSPENDED) {
- udev->skip_sys_resume = 1;
+ if (udev->parent || udev->speed != USB_SPEED_HIGH)
+ udev->skip_sys_resume = 1;
return 0;
}
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 57aeca160f3..a42db75c233 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2890,7 +2890,13 @@ loop:
static int hub_thread(void *__unused)
{
+ /* khubd needs to be freezable to avoid intefering with USB-PERSIST
+ * port handover. Otherwise it might see that a full-speed device
+ * was gone before the EHCI controller had handed its port over to
+ * the companion full-speed controller.
+ */
set_freezable();
+
do {
hub_events();
wait_event_freezable(khubd_wait,