1USB_AUTOPM_GET_INTER(9)          USB Core APIs         USB_AUTOPM_GET_INTER(9)
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NAME

6       usb_autopm_get_interface - increment a USB interface´s PM-usage counter
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SYNOPSIS

9       int usb_autopm_get_interface(struct usb_interface * intf);
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ARGUMENTS

12       intf
13           the usb_interface whose counter should be incremented
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DESCRIPTION

16       This routine should be called by an interface driver when it wants to
17       use intf and needs to guarantee that it is not suspended. In addition,
18       the routine prevents intf from being autosuspended subsequently. (Note
19       that this will not prevent suspend events originating in the PM core.)
20       This prevention will persist until usb_autopm_put_interface is called
21       or intf is unbound. A typical example would be a character-device
22       driver when its device file is opened.
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24       The routine increments intf´s usage counter. (However if the autoresume
25       fails then the counter is re-decremented.) So long as the counter is
26       greater than 0, autosuspend will not be allowed for intf or its
27       usb_device. When the driver is finished using intf it should call
28       usb_autopm_put_interface to decrement the usage counter and queue a
29       delayed autosuspend request (if the counter is <= 0).
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31       Note that intf->pm_usage_cnt is owned by the interface driver. The core
32       will not change its value other than the increment and decrement in
33       usb_autopm_get_interface and usb_autopm_put_interface. The driver may
34       use this simple counter-oriented discipline or may set the value any
35       way it likes.
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37       Resume method calls generated by this routine can arrive at any time
38       while intf is suspended. They are not protected by the usb_device´s
39       lock but only by its pm_mutex. Drivers must provide their own
40       synchronization.
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42       This routine can run only in process context.
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45Kernel Hackers Manual 2.6.         June 2019           USB_AUTOPM_GET_INTER(9)
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