Attempting to answer my own question...
Phil Endecott wrote:
Greg KH wrote:
On Mon, Dec 03, 2007 at 06:19:53PM +0000, Phil Endecott wrote:
Dear Experts,
Can anyone suggest the best way to determine the speed (low/full/high) at
which a device is operating from user-space?
usbdevice_fs has 'connectinfo', which seems to return a flag for low-speed
operation. But it doesn't seem to distinguish between full and high-speed.
A usbdevicefs method would be ideal as I'm already using that, but maybe
there is something in /sys?
Yes, there's a "speed" file there, try it out, I think it's exactly what
you are looking for :)
Thanks Greg. I should have spotted that; I must have been lost in
/sys's maze of twisty symlinks.
Now I just need to work out how to convert from e.g.
/proc/bus/usb/001/010 to e.g.
/sys/devices/pci0000:00/0000:00:10.3/usb1/1-4/1-4.6/1-4.6.3. Any ideas?
(Sometimes I already have the /sys path; my app listens for uevents on
a netlink socket, and these include both pathnames. But when it starts
it looks for already-attached devices by iterating through
/proc/bus/usb, and in this case it doesn't have the /sys path
conveniently available. Maybe I should instead do this initial search
in some other way, e.g. through /sys/bus/usb/devices?)
I think I need to iterate through /sys/bus/usb/devices, skipping the
"usb*" and "*:*" files; in each case I can get the bus number from the
first bit of the directory name, and the device number from the devnum
file in that directory. Example:
for i in /sys/bus/usb/devices/*
do
case `basename $i` in
usb*) ;;
*:*) ;;
*) bus=`basename $i | sed 's/-.*$//g'`
device=`cat $i/devnum`
speed=`cat $i/speed`
echo "/proc/bus/usb/${bus}/${device} ${speed}"
esac
done
Output:
/proc/bus/usb/1/2 480
/proc/bus/usb/1/4 1.5
/proc/bus/usb/1/3 12
This looks sane to me apart from the obvious lack of leading zeros.
Phil.
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