Hi Roger-san, < snip > > >>>> commit 11c011a5e777c83819078a18672543f04482b3ec > >>>> Author: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx> > >>>> Date: Thu May 19 11:12:56 2016 +0100 > >>>> > >>>> usb: echi-hcd: Add ehci_setup check before echi_shutdown > >>>> > >>>> > >>>> > >>>> In some cases, the USB code (gadget/hcd->start/stop) needs to be called > >>>> during the role swap. For example, if you have mux driver, you may > >>>> need to call usb_remove_hcd when ID from 0 to 1. Without Roger's framework, > >>>> how can we do that? > >>> > >>> You don't really need to remove the gadget. Just mask its interrupts and > >>> ignore any calls to any gadget_driver ops, right? Likewise for > >>> XHCI. Just clear RUN/STOP and no events will ever reach XHCI. But, from > >>> the point of view of dwc3, it's simpler to unregister the platform > >>> device we create for xhci-plat.c. I need no changes in XHCI to do that > >>> and driver model will make sure to call xhci-plat's ->remove() which > >>> will handle everything for me correctly. > >>> > >> > >> I admit it can do in a IP driver, eg both host and peripheral for the > >> single IP, eg chipidea, dwc3, etc. But how can we clear RUN/STOP bit > >> or what else for HCD at mux driver? > > > > dwc3's OTG block has control of that, however, what I'll do is > > platform_device_del() xhci-plat's device. Not one line changes inside > > XHCI. > > > > Let's talk about how non dwc3 based platforms can get it done. > > Yoshihiro-san, could you please share your platform requirements from dual-role > perspective? My platform requirements about dual-role are: - Initial settings of all host, gadget and OTG IP registers are needed before enters [AB]-device recognition procedure. - In the recognition procedures, a software needs: - to check ID pin related register in OTG - to set OTG IP registers to change the role - and then host or gadget can start. - In the disconnect detection procedures, a software needs similar checkings/settings with the recognition. Best regards, Yoshihiro Shimoda > cheers, > -roger -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
