On Sun, Nov 17, 2024 at 08:44:16PM +0800, Markus Rechberger wrote: > Basically the issue comes from hub_port_connect. > > drivers/usb/core/hub.c > > hub_port_init returns -71 -EPROTO and jumps to loop > https://github.com/torvalds/linux/blob/master/drivers/usb/core/hub.c#L5450 > > I'd question if usb_ep0_reinit is really required in loop which is > running following functions: > usb_disable_endpoint(udev, 0 + USB_DIR_IN, true); > usb_disable_endpoint(udev, 0 + USB_DIR_OUT, true); > usb_enable_endpoint(udev, &udev->ep0, true); > > this is something only experience over the past decades can tell? > > usb_enable_endpoint will trigger xhci_endpoint_reset which doesn't do > much, but crashes the entire system with the upstream kernel when it > triggers xhci_check_bw_table). > > I removed usb_ep0_reinit here and devices are still workable under > various conditions (again I shorted and pulled D+/D- to ground for > testing). > The NULL PTR check in xhci_check_bw_table would be a second line of > defense but as indicated in the first mail it shouldn't even get there. > > > > As a second issue I found in usb_reset_and_verify device > https://github.com/torvalds/linux/blob/master/drivers/usb/core/hub.c#L6131 > > ret = hub_port_init(parent_hub, udev, port1, i, &descriptor); > if (ret >= 0 || ret == -ENOTCONN || ret == -ENODEV) { > break; > } > > hub_port_init can also return -71 / -EPROTO, the cases should be very > rare when usb_reset_and_verify_device is triggered and that happens. > > > I'm just waiting for comments now since this is some critical piece of > infrastructure code before proceeding with a patch. Send us a patch and we will be glad to review it. thanks! greg k-h
