This article may tell you more about what you need https://www.baeldung.com/linux/control-usb-power-supply
-T On Tue, Jan 23, 2024, 12:35 Tomas Kuchta <tomas.kuchta.li...@gmail.com> wrote: > echo 1 > /sys/bus/usb/drivers/usb/bind > > Will bind it again. The side effect of unbind+bind is usb bus/device > reset, depending on whether you are addressing bus or device > > The number(s) being echoed means: > usbBusNo usbPort usbDevice > Check the bus/device format in /sys or dmsg or .... > > There is old article from GKH about how this worked in 2.6 kernels ages > ago. It has changed somewhat and improved - see usb kernel sub-system > documentation or google for more details. > > https://lwn.net/Articles/143397/ > > I am typing this on my cell, using google and memory - I was not able to > verify current format on my system at home and I use remote multi-user > centOS at work (cannot mess with that) > > Good luck, -T > > > On Tue, Jan 23, 2024, 11:24 Vince Winter <thine.technoc...@gmail.com> > wrote: > >> It is also about the power draw on the processor power and the system >> power >> from having a USB controller working. Having any USB plugged adds >> noticeable amount of power. >> >> I am hoping that telling the kernel, as per the suggestions here, to >> unpower it that the controller goes back to "sleep mode". Also it would be >> convenient if can I bring the device backup with out unplugging it. >> >> When I have a moment at work, I will get some empirical data if this works >> or not. >> >> On Tue, Jan 23, 2024, 5:51 AM Tomas Kuchta <tomas.kuchta.li...@gmail.com> >> wrote: >> >> > On Tue, Jan 23, 2024, 01:00 Ted Mittelstaedt <t...@portlandia-it.com> >> > wrote: >> > >> > > I've messed with this before trying to troubleshoot USB cams. >> > > >> > > It's highly dependent on the USB hardware. Not all USB devices >> implement >> > > "low power" mode. >> > > >> > > Your best shot is to get a good USB 4 port hub - not a crappy one - a >> > good >> > > one and the good ones >> > > Implement power control and can cut power to a USB device if you >> command >> > > them to. >> > > . >> > >> > >> > This is not about how the USB devices (mis)behave. They would not be >> trying >> > to control the devices, but the USB host(s) in the PC/laptop, I presume. >> > >> > USB host can, and will cut power to the bus when directed. >> > >> > While I am as guilty as any man - the world really sucks when people who >> > think they understand stuff speak with undoubted authority about stuff. >> > >> > Hole it helps, -T >> > >> > > >> > >> >
