On Mon, 2019-08-05 at 12:06 +0200, Linus Walleij wrote: > On Wed, Jul 24, 2019 at 10:51 AM Chunfeng Yun <chunfeng....@mediatek.com> > wrote: > > > Because the USB Connector is introduced and the requirement of > > usb-connector.txt binding, the old way using extcon to support > > USB Dual-Role switch is now deprecated, meanwhile there is no > > available common driver when use Type-B connector, typically > > using an input GPIO to detect USB ID pin. > > However while this was going on, > drivers/extcon/extcon-fsa9480.c was merged and that detects > not only GPIO on the USB port but multiplexed usecases such > as UART over the USB micro PHY (and no that UART is not > a USB UART, but an actual RX/TX over D-/D+). > > That driver also measure a whole slew of funny resistance > values on the ID pin, that is how it does its job. I look into the spec of fsa9480, it indeed detect many USB accessories. But this driver is used for simplest cases that only uses micro receptacle with id-pin/vbus-pin
> > But for just "hey I'm plugged in" we can surely keep this > ID on GPIO detection in the USB subsystem. Sorry, you mean provide a common API? could you please describe more clearer about your suggestion? Introducing a single driver using usb_role_switch will help to keep transparent for USB controller driver, no matter it uses type-c or micro Thanks a lot > > I just get a bit insecure about how we should ideally > handle these "funny-PHY's". > > Yours, > Linus Walleij
