I'm perfectly aware the USB host can cut power to the bus and to an individual device on the bus. That's why I even got involved with it in the first place. I had multiple USB devices that would STOP WORKING for no flipping reason and my hope was I could duplicate a removal/insertion with a script without having to actually unplug and plug in stuff.
I'm also perfectly aware due to actually spending time using these commands - unlike you, apparently - That when you turn the bus or attempt to turn the device back on after cutting power to it - that many times The device WILL NOT come back on until it's unplugged and plugged back in. Do I know why it works with some hardware and not others? And some combinations and not others? And some PC's and not others? Why, yes. Yes I do. It's because it's crap. USB is easily the WORST engineered interface ever invented with computers. They only finally got the hardware connection right after something like 5 different tries with a connector ultimately produced USB-C and the standard still sucks with grey areas in it. As I said USB put the BS into computer cabling. The world really sucks when people who think they understand stuff DUE TO BOOK LARNIN speak with undoubted authority about stuff THAT THEY HAVE NEVER ACTUALLY ATTEMPTED IN PRACTICE. Ted -----Original Message----- From: PLUG <plug-boun...@lists.pdxlinux.org> On Behalf Of Tomas Kuchta Sent: Tuesday, January 23, 2024 5:51 AM To: Portland Linux/Unix Group <plug@lists.pdxlinux.org> Subject: Re: [PLUG] How to script USB device detection 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 >
