On Thu, 21 Jan 2021 14:29:29 -0500 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > I'm also concerned about regressions. This is a legacy class driver, > > only used where CUPS is not applicable, mostly with truly ancient > > devices. So yes, setting a zero altsetting after enumeration should > > be unnecessary. But you never know with the old firmware. > How about skipping the call whenever the interface has only one > altsetting? Do you mean when it's only one and not equal to zero? BTW, one other thing bothers me. Jeremy confirmed that my patch worked, which skips the call when USB_QUIRK_NO_SET_INTF is set. But if we look into drivers/usb/core/message.c, the control exchange to set the altsetting is skipped in that case anyway. So, usblp was calling usb_set_protocol, the suspect control was skipped, but something else caused a problem. Could it be the attempt to clear halt that triggered the problem? -- Pete
