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| author | Alan Stern <stern@rowland.harvard.edu> | 2007-11-16 19:58:15 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-11-29 00:58:34 +0300 |
| commit | 3c886c50486cfbef2a2382b99bf4083a465c970a (patch) | |
| tree | e7482b8fd40791db70d1b241ec23d0cd6267c401 /Documentation/usb | |
| parent | bc59462b80c694670fbb5d0bb1a8450ffc353080 (diff) | |
| download | linux-3c886c50486cfbef2a2382b99bf4083a465c970a.tar.xz | |
USB: power-management documenation update
This patch (as1014) was partly written by Tilman Schmidt. It
clarifies the USB power-management documentation by explaining that
when a disconnect occurs, a suspend method call might not be followed
by either a resume or a reset_resume call.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation/usb')
| -rw-r--r-- | Documentation/usb/power-management.txt | 8 |
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 |