On Sun, Jan 23, 2022 at 12:59:21PM +0100, Helge Deller wrote: > On 1/23/22 12:07, Greg Kroah-Hartman wrote: > > On Sun, Jan 23, 2022 at 11:40:01AM +0100, Helge Deller wrote: > >> On all kernels 5.15.x and 5.16.x I noticed that resetting > >> the USB devices with this shell script: > >> > >> for i in $(ls /sys/bus/pci/drivers/ahci/|grep :) > >> do > >> echo $i > >> echo $i >/sys/bus/pci/drivers/ahci/unbind > >> sleep 1 > >> echo $i >/sys/bus/pci/drivers/ahci/bind > >> done > > > > That is dangerous to do, why do this? All of your block devices might > > have disappeard. > > > >> # reseting USB3 ports (if there none you'll get errors) > >> for i in $(ls /sys/bus/pci/drivers/xhci_hcd/|grep :) > >> do > >> echo $i > >> echo $i >/sys/bus/pci/drivers/xhci_hcd/unbind > >> sleep 1 > >> echo $i >/sys/bus/pci/drivers/xhci_hcd/bind > >> done > > > > Again, why do this at all? > > I need to reset some of the USB devices after a suspend/resume cycle. The devices, or the host controllers? They are different things. > The problem is, that some of the USB devices are > handed over into a running VirtualBox VM and after > the suspend/resume they need to be virtually plugged out/in > so that the running Windows VM will reconnect them. unbind/bind is a very harsh way of doing this. but do it on the USB devics, not the host controllers. > If you search in the internet, you will find many places > where this unbind/bind process is mentioned, e.g.: > https://askubuntu.com/questions/645/how-do-you-reset-a-usb-device-from-the-command-line > This procedure did worked in the past. Never trust the internet :) But note, there is a usbreset program mentioned there, which is part of 'usbutils' and should already be installed on your machine. Why not just use that? > I think the main problem is, that it's somehow unexpected that > the SATA controllers are logically attached to the USB > controllers. Huh? No they are not. 'ahci' is a SATA controller. 'xhci' is a USB controller. Two totally different things. > So, if you believe to unbind "just" the USB devices you > suddenly unbind SATA controllers too. Again, no, you are unbinding two different things here. And a USB host controller is different than individual USB devices as well. > >> immediately leads to a non-functional system, because the discs > >> face I/O errors and will switch to read-only mode. > > > > Sure, the disks are gone, this is expected. > > Ok. > > >> Effectively I have to reboot the machine. > > > > I'm amazed it keeps working at all. > > :-) > > >> It's reproduceable for me on two completely different x86 machines with > >> different USB devices. > > > > What do you expect this to do instead? You just disabled all block > > controllers in your system, followed by all USB controllers. And then > > attempted to add them back, but given that the old devices still had > > userspace references on them, the devices will come back with different > > names and so you need to mount them again. > > > > So this looks like it is working as intended. Just don't do this :) > > Ok, sure, but I think it's unexpected that the SATA ports are listed > beneath the USB controllers, beside USB devices. Where are they listed like that? > If I run "lsusb", the SATA controllers don't show up either. That is because they are independant and have nothing to do with each otner. > They are listed when I run "lspci". > Shouldn't they maybe show up somewhere else, e.g. > /sys/bus/pci/drivers/sata/* The controllers are PCI drivers. The block devices they create are scsi devices (through the ata system). This has nothing to do with USB. confused, greg k-h
