Hi, >On Thu, Jan 10, 2019 at 09:30:41AM +0800, Peter Chen wrote: >> On Mon, Dec 24, 2018 at 12:44 AM Pawel Laszczak <pawell@xxxxxxxxxxx> wrote: >> - debugfs is nice to have feature, I suggest removing it at this >> initial version. Besides, role switch >> through /sys is normal feature, the end user may use it at real >> product, so, it is better at device's >> /sys entry instead of debugfs. >> >> - I don't know why you add "disable" at debugfs, please comment. > >As you imply here, no real-world functionality should ever be in >debugfs as it is an optional system component and kernel code should >work just fine without it being enabled (as more and more systems are >disabling it due to the obvious security problems it has.) > "disable" it's not required. It's used for testing. It allows to enable/disable the current role. It can be used for testing eg. connect/disconnect event. I mainly test the driver remotely and I can't do connect/disconnect by USB cable. "disable" allow me to get trace log from host/device without disconnecting cable: I'm using the fallowing sequence: - load cdns3.ko modules - echo 1 > disable - disable current role - echo cdns3:* tracing/set_event - echo 0 > disable - enable role again - cat tracing/trace. Pawel
