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USB: documentation update for the pre_reset method

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This patch (as1459) updates the documentation for the pre_reset method
in struct usb_driver.  When a driver is notified of an impending
reset, it must cancel all outstanding I/O and not start any new I/O
until it has been notified that the reset is complete.

As far as I know, most existing drivers that implement pre_reset do
this now.  The major exceptions appear to be the SpeedTouch and
CDC-WDM drivers.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2011-04-28 10:45:24 -04:00 committed by Greg Kroah-Hartman
parent 15b2f3204a
commit 6498d9db6d
2 changed files with 9 additions and 5 deletions
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8
Documentation/usb/callbacks.txt
View File

@ -95,9 +95,11 @@ pre_reset
int (*pre_reset)(struct usb_interface *intf);
Another driver or user space is triggering a reset on the device which
contains the interface passed as an argument. Cease IO and save any
device state you need to restore.
A driver or user space is triggering a reset on the device which
contains the interface passed as an argument. Cease IO, wait for all
outstanding URBs to complete, and save any device state you need to
restore. No more URBs may be submitted until the post_reset method
is called.
If you need to allocate memory here, use GFP_NOIO or GFP_ATOMIC, if you
are in atomic context.

6
include/linux/usb.h
View File

@ -806,8 +806,10 @@ struct usbdrv_wrap {
* @resume: Called when the device is being resumed by the system.
* @reset_resume: Called when the suspended device has been reset instead
* of being resumed.
* @pre_reset: Called by usb_reset_device() when the device
* is about to be reset.
* @pre_reset: Called by usb_reset_device() when the device is about to be
* reset. This routine must not return until the driver has no active
* URBs for the device, and no more URBs may be submitted until the
* post_reset method is called.
* @post_reset: Called by usb_reset_device() after the device
* has been reset
* @id_table: USB drivers use ID table to support hotplugging.