On Sun, Jun 05, 2016 at 04:46:55PM +0800, Lu Baolu wrote: > Hi, > > On 06/05/2016 04:33 PM, Jun Li wrote: > >> Port mux is part of dual role switch, but not the whole thing. > >> > > >> > Dual role switch includes at least below things: > >> > - ID or type-C event detection > >> > - port mux > >> > - VBUS management > >> > - start/stop host/device controllers > >> > > >> > An OTG/Dual-role framework can be used to keep all these things run > >> > together with an internal state machine. But it's not duplicated with a > >> > generic framework for port mux and the port mux drivers. > >> > > >>> > > Your > >>> > > case is just like Renesas case, which uses two different drivers > >>> > > between peripheral and host[1]. > >> > > >> > In my case, the port mux devices are physical devices and they can be > >> > controlled through GPIO pins or device registers. They are independent of > >> > both peripheral and host controllers. > >> > > > I also think current OTG/Dual role framework can support your case, if you > > find there is any limitation of it which can't meet your requirement, we > > should improve it, Roger also provide an example of dual role switch with > > USB3 based on his OTG core. > > Why do we need an OTG framework to support a device driver?
Just like you said above, OTG framework can manage role switch, the role switch may need to start or stop host/gadget driver according to different hardware signals or user input. > Is it something like a bus or class driver? The DRD/OTG framework uses the same device structure with the caller, the caller can be a dual-role controller driver (like dwc3, chipidea, etc), or a separate switch driver which like your mux port driver. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
