Good afternoon, this is my first post here. I have tried in vain to get
answers elsewhere so I hope you can help me.
I would like to know the correct way to override USB power budgets.
I have a device that reports that it requires 510 mA. I've read that
this number is reported because it is what 255 represents and the device
designer probably thought they could get away with setting the maximum
8-bit value into "MaxPower". Obviously now that power requirements are
checked, they can't.
This does not help me - I have a device that was working just fine but
ceased working after a kernel update.
I have read that power checking can be overriden by writing a 1 to the
file /sys/bus/usb/devices/2-6.1.3/bConfigurationValue. This doesn't
work: it just increases the allowance to 500ma which still falls short
by 10ma.
My /var/log/messages upon plugging in the device
Dec 20 14:19:51 tma1 kernel: [192154.688351] usb 2-6.1.3: new full speed
USB device using ehci_hcd and address 28
Dec 20 14:19:51 tma1 kernel: [192154.803529] usb 2-6.1.3: rejected 1
configuration due to insufficient available bus power
Dec 20 14:19:51 tma1 kernel: [192154.803532] usb 2-6.1.3: no
configuration chosen from 1 choice
And after setting bConfigurationValue:
root:~# echo -n 1 >/sys/bus/usb/devices/2-6.1.3/bConfigurationValue
Dec 20 14:20:53 tma1 kernel: [192216.854959] usb 2-6.1.3: new config #1
exceeds power limit by 10mA
I would like to know how to completely override this checking, or how to
supply another configuration choice that I can configure to allow 510ma.
Some details:
root@tma1:~# uname -a
Linux tma1 2.6.24-24-openvz #1 SMP Fri Sep 18 18:49:50 UTC 2009 x86_64
GNU/Linux
root@tma1:~# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=8.04
DISTRIB_CODENAME=hardy
DISTRIB_DESCRIPTION="Ubuntu 8.04.3 LTS"
Many thanks,
John Lane
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
