On 1/23/22 12:59, 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 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. > > 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. > > I think the main problem is, that it's somehow unexpected that > the SATA controllers are logically attached to the USB > controllers. > So, if you believe to unbind "just" the USB devices you > suddenly unbind SATA controllers too. > >>> 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. > If I run "lsusb", the SATA controllers don't show up either. > They are listed when I run "lspci". > Shouldn't they maybe show up somewhere else, e.g. > /sys/bus/pci/drivers/sata/* Ignore this. AHCI = SATA... Sorry for the noise. Helge
