Hi Peter, On 06/06/2016 10:05 AM, Peter Chen wrote: > 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. We don't have any OTG or dual-role (reduced OTG) capable controllers. So we don't need to aid OTG framework to start/stop host/gadget drivers. > >> 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. > >From my point of view, this isn't the right way to handle a port mux device. We have many kinds of port mux devices across multiple archs, we should have a generic framework for them, so that consumers, (like OTG framework) can manipulate port mux devices through a common interfaces. Just like we already have frameworks for PHY, VBUS regulator and ... Best regards, Lu Baolu -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
