2007-01-01 20:56:30

by Andrew J. Barr

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Subject: Cut power to a USB port?

I have a simple question perhaps someone can help me with here...

I have one of those simple LED keyboard lamps that get their power from
the USB port. Is there some way in Linux, using files under /sys I would
imagine, to cut power to the USB port into which this lamp is plugged? I
know I would have to manually figure out what port it's plugged into, as
it is not a "real" USB device...e.g. it just draws power. I would like
to be able to programmatically switch the lamp on and off.

Thanks in advance,
Andrew Barr

Please CC any replies


2007-01-01 21:52:04

by Oliver Neukum

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Subject: Re: Cut power to a USB port?

Am Montag, 1. Januar 2007 21:56 schrieb Andrew Barr:
> I have a simple question perhaps someone can help me with here...
>
> I have one of those simple LED keyboard lamps that get their power from
> the USB port. Is there some way in Linux, using files under /sys I would
> imagine, to cut power to the USB port into which this lamp is plugged? I

You could use usbfs to send commands to the hub.

> know I would have to manually figure out what port it's plugged into, as
> it is not a "real" USB device...e.g. it just draws power. I would like
> to be able to programmatically switch the lamp on and off.

The ability to cut each port's power individually is optional. Your
hardware may well be incapable of what you want.

Regards
Oliver

2007-01-02 08:58:32

by Greg KH

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Subject: Re: Cut power to a USB port?

On Mon, Jan 01, 2007 at 03:56:25PM -0500, Andrew Barr wrote:
> I have a simple question perhaps someone can help me with here...
>
> I have one of those simple LED keyboard lamps that get their power from
> the USB port. Is there some way in Linux, using files under /sys I would
> imagine, to cut power to the USB port into which this lamp is plugged? I
> know I would have to manually figure out what port it's plugged into, as
> it is not a "real" USB device...e.g. it just draws power. I would like
> to be able to programmatically switch the lamp on and off.

Search the archives of the linux-usb-devel mailing list for a program
that might do this for you (depending on your hardware.)

good luck,

greg k-h

2007-01-02 15:28:44

by Andrew J. Barr

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Subject: Re: Cut power to a USB port?

On Tue, 2007-01-02 at 00:32 -0800, Greg KH wrote:
> On Mon, Jan 01, 2007 at 03:56:25PM -0500, Andrew Barr wrote:
> > I have a simple question perhaps someone can help me with here...
> >
> > I have one of those simple LED keyboard lamps that get their power from
> > the USB port. Is there some way in Linux, using files under /sys I would
> > imagine, to cut power to the USB port into which this lamp is plugged? I
> > know I would have to manually figure out what port it's plugged into, as
> > it is not a "real" USB device...e.g. it just draws power. I would like
> > to be able to programmatically switch the lamp on and off.
>
> Search the archives of the linux-usb-devel mailing list for a program
> that might do this for you (depending on your hardware.)

What search terms should I use? Searching on "power" and "port power" at
Gmane in the gmane.linux.usb.devel group doesn't readily give me
anything.

For the record, my hardware:

00:1d.0 USB Controller: Intel Corporation 82801DB/DBL/DBM
(ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 01)
00:1d.1 USB Controller: Intel Corporation 82801DB/DBL/DBM
(ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 (rev 01)
00:1d.2 USB Controller: Intel Corporation 82801DB/DBL/DBM
(ICH4/ICH4-L/ICH4-M) USB UHCI Controller #3 (rev 01)
00:1d.7 USB Controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2
EHCI Controller (rev 01)

IBM Thinkpad R51 2883-ELU.

Regards,
Andrew

> good luck,
>
> greg k-h

2007-01-02 16:50:19

by Randy Dunlap

[permalink] [raw]
Subject: Re: Cut power to a USB port?

On Tue, 02 Jan 2007 10:28:38 -0500 Andrew Barr wrote:

> On Tue, 2007-01-02 at 00:32 -0800, Greg KH wrote:
> > On Mon, Jan 01, 2007 at 03:56:25PM -0500, Andrew Barr wrote:
> > > I have a simple question perhaps someone can help me with here...
> > >
> > > I have one of those simple LED keyboard lamps that get their power from
> > > the USB port. Is there some way in Linux, using files under /sys I would
> > > imagine, to cut power to the USB port into which this lamp is plugged? I
> > > know I would have to manually figure out what port it's plugged into, as
> > > it is not a "real" USB device...e.g. it just draws power. I would like
> > > to be able to programmatically switch the lamp on and off.
> >
> > Search the archives of the linux-usb-devel mailing list for a program
> > that might do this for you (depending on your hardware.)
>
> What search terms should I use? Searching on "power" and "port power" at
> Gmane in the gmane.linux.usb.devel group doesn't readily give me
> anything.

You can try:

usbpoweroff.c
(http://www.informatik.uni-halle.de/~ladischc/usbpoweroff.c)
or
hub-ctrl-2.c (http://www.gniibe.org/log/linux)

> For the record, my hardware:
>
> 00:1d.0 USB Controller: Intel Corporation 82801DB/DBL/DBM
> (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 01)
> 00:1d.1 USB Controller: Intel Corporation 82801DB/DBL/DBM
> (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 (rev 01)
> 00:1d.2 USB Controller: Intel Corporation 82801DB/DBL/DBM
> (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #3 (rev 01)
> 00:1d.7 USB Controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2
> EHCI Controller (rev 01)
>
> IBM Thinkpad R51 2883-ELU.


---
~Randy

2007-01-02 17:08:43

by Andrew J. Barr

[permalink] [raw]
Subject: Re: Cut power to a USB port?

On Tue, 2007-01-02 at 08:36 -0800, Randy Dunlap wrote:
> On Tue, 02 Jan 2007 10:28:38 -0500 Andrew Barr wrote:
>
> > On Tue, 2007-01-02 at 00:32 -0800, Greg KH wrote:
> > > On Mon, Jan 01, 2007 at 03:56:25PM -0500, Andrew Barr wrote:
> > > > I have a simple question perhaps someone can help me with here...
> > > >
> > > > I have one of those simple LED keyboard lamps that get their power from
> > > > the USB port. Is there some way in Linux, using files under /sys I would
> > > > imagine, to cut power to the USB port into which this lamp is plugged? I
> > > > know I would have to manually figure out what port it's plugged into, as
> > > > it is not a "real" USB device...e.g. it just draws power. I would like
> > > > to be able to programmatically switch the lamp on and off.
> > >
> > > Search the archives of the linux-usb-devel mailing list for a program
> > > that might do this for you (depending on your hardware.)
> >
> > What search terms should I use? Searching on "power" and "port power" at
> > Gmane in the gmane.linux.usb.devel group doesn't readily give me
> > anything.
>
> You can try:
>
> usbpoweroff.c
> (http://www.informatik.uni-halle.de/~ladischc/usbpoweroff.c)
> or
> hub-ctrl-2.c (http://www.gniibe.org/log/linux)

Hm, my hardware must not support it. The hub-ctrl-2.c program fails with
a broken pipe and the usbpoweroff.c program silently does nothing,
exiting returning zero.

Thanks to you all anyway,
Andrew

> > For the record, my hardware:
> >
> > 00:1d.0 USB Controller: Intel Corporation 82801DB/DBL/DBM
> > (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 01)
> > 00:1d.1 USB Controller: Intel Corporation 82801DB/DBL/DBM
> > (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 (rev 01)
> > 00:1d.2 USB Controller: Intel Corporation 82801DB/DBL/DBM
> > (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #3 (rev 01)
> > 00:1d.7 USB Controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2
> > EHCI Controller (rev 01)
> >
> > IBM Thinkpad R51 2883-ELU.
>
>
> ---
> ~Randy