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-rw-r--r--Documentation/usb/power-management.txt8
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/usb/power-management.txt b/Documentation/usb/power-management.txt
index 97842deec471..b2fc4d4a9917 100644
--- a/Documentation/usb/power-management.txt
+++ b/Documentation/usb/power-management.txt
@@ -278,6 +278,14 @@ optional. The methods' jobs are quite simple:
(although the interfaces will be in the same altsettings as
before the suspend).
+If the device is disconnected or powered down while it is suspended,
+the disconnect method will be called instead of the resume or
+reset_resume method. This is also quite likely to happen when
+waking up from hibernation, as many systems do not maintain suspend
+current to the USB host controllers during hibernation. (It's
+possible to work around the hibernation-forces-disconnect problem by
+using the USB Persist facility.)
+
The reset_resume method is used by the USB Persist facility (see
Documentation/usb/persist.txt) and it can also be used under certain
circumstances when CONFIG_USB_PERSIST is not enabled. Currently, if a