Messages in this thread | | | Date | Sat, 4 Sep 1999 20:13:31 -0500 (CDT) | From | Drew Bernat <> | Subject | Re: USB state change notification to user space |
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On Sat, 4 Sep 1999, Johannes Erdfelt wrote:
> I'd like to offer a way for user level programs to be informed of state > changes on the USB bus. (ie device plugging in, device unplugging, new > bus registered) > > I can think of a couple of ways to provide this, but I'm unsure what > would be the favored way of doing it. > > 1) opening /dev/bus/usb and poll'ing on read, then rescanning the > /proc/bus/<busno> directory to find the change. Kinda weird doing file > type things on a directory tho > 2) opening /dev/bus/usb/devices and poll'ing on read, then rescanning > the /proc/bus/<busno> directory to find the change > 3) opening /dev/bus/usb/devices and use a blocking ioctl > > I can't think of anything which is similar enough in the kernel that I > could mimick.
A fourth possibility is some sort of signal, which makes sense in a way -- do we want the application to a) ask if there is a new device, b) wait for a new device, or c) be notified that there is a new device? It wouldn't be hard (I think) to write a callback function for the USB handler that an application can register with (i.e. a signal). It seems to me that option c) is the best, since it maps to the bus behavior best.
Drew
-- Drew Bernat __ ____ abernat@zathras.net | | | http://www.zathras.net | |
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