On 28.8.2020 18.55, Alan Stern wrote: > On Fri, Aug 28, 2020 at 04:10:47PM +0300, Mathias Nyman wrote: >>>> Thanks, that seems to work! (Judging by the absence of my original >>>> issue with the xum1541 adapter; I haven't checked what's actually >>>> happening on the bus). >>>> >>>> Martin >>>> >>> >>> Great, thanks. >>> >>> Now this test code needs to be cleaned up a turned into a real patch >> >> Can you test one more round? >> The code below is cleaned up but it also has a functional change. >> This version issues separate commands for dropping and adding endpoints. >> Previous code both did all on one command. >> >> If it works I'll send it forward. >> >> Thanks >> -Mathias >> >> --- >> From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> >> Subject: [PATCH] usb: Fix out of sync data toggle if a configured device is >> reconfigured >> >> Userspace drivers that use a SetConfiguration() request to "lightweight" >> reset a already configured usb device might cause data toggles to get out >> of sync between the device and host, and the device becomes unusable. >> >> The xHCI host requires endpoints to be dropped and added back to reset the >> toggle. USB core avoids these otherwise extra steps if the current active >> configuration is the same as the new requested configuration. >> >> A SetConfiguration() request will reset the device side data toggles. >> Make sure usb core drops and adds back the endpoints in this case. >> >> To avoid code duplication split the current usb_disable_device() function >> and reuse the endpoint specific part. >> >> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> > > This seems reasonable. But can you add something to the kerneldoc for > usb_reset_configuration() explaining that if the routine fails, the > device will probablly be in an unusable state (endpoints disabled, > interfaces only partially enabled)? > > Alan Stern > Good point, will add Thanks Mathias
