On 1/23/22 13:33, Greg Kroah-Hartman wrote: > 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. Right, and that was my fault. I mixed up "ahci" and "ehci" (the USB2.0 controller). So, my report was bogus. Please ignore. Helge
