Hi guys, On Wed, Dec 13, 2017 at 10:43:50AM +0800, Peter Chen wrote: > On Wed, Dec 13, 2017 at 01:17:23AM +0000, Takashi Matsuzawa wrote: > > Hello. > > > > >If you have a Type-C connector on your board, then you also should > > >have a USB Type-C PHY that takes care of CC logic. The host-to-device > > >relationship is determined using the Configuration Channel (CC) that > > >goes through the USB Type-C cable. Note that CC is not the same as ID! > > > > I am playing with i.MX6 pico board, which has USB-OTG receptacle with USB-C physical shape. > > http://download.wandboard.org/hobbitboard-imx6ul/documentation/pico-imx6ul-emmc-hobbit-reva1-hardware-manual-20160328.pdf OK, from those schematics we can clearly see that the CC lines are really connected to the USB_OTG_ID signal. I guess the idea has been to attempt to get the USB_OTG_ID signal pulled down to ground when the partner is UFP (device) and has the CC line connected to the ground with the resistor Rd. That should put the board into host mode, but I guess it's not working. With Type-C to Type-C connections, in case the partner is DFP (host) or DRP (dual-role), that configuration will just confuse the partner. The partner will now see that the CC is pulled high and probable think that your board is also DFP (host), i.e. your board and the partner connected to it, both think they need to be in device mode. I don't think there are actually any guarantees that connecting the CC lines to the ID input on the board will work in any scenario. There really should be a CC-logic chip if dual-role support was needed. For device mode only, simply connecting the CC lines to the ground from the connector would have been enough. > > I think the USB-OTG PHY is part of i.MX6UL SoC? > > Yes, but it is just USB PHY, not PD PHY. You need external pure CC-logic > chip (like PTN5150), or Type-C PD chip (like PTN5110) to support CC > or PD event. Oh cool, PTP5150 seems to function autonomously if needed! So it would have worked even without driver support initially. Cheers, -- heikki -- 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
