On Tue, Jul 14, 2015 at 11:18:30AM -0700, Andrew Bresticker wrote: > Hi Peter, > > On Mon, Jul 13, 2015 at 5:59 PM, Peter Chen <peter.chen@xxxxxxxxxxxxx> wrote: > > On Mon, Jul 13, 2015 at 12:14:43PM -0700, Andrew Bresticker wrote: > >> Hi Roger, > >> > >> On Wed, Jul 8, 2015 at 3:19 AM, Roger Quadros <rogerq@xxxxxx> wrote: > >> > Usage model: > >> > ----------- > >> > > >> > - The OTG controller device is assumed to be the parent of > >> > the host and gadget controller. It must call usb_otg_register() > >> > before populating the host and gadget devices so that the OTG > >> > core is aware that it is an OTG device before the host & gadget > >> > register. The OTG controller must provide struct otg_fsm_ops * > >> > which will be called by the OTG core depending on OTG bus state. > >> > >> I'm wondering if the requirement that the OTG controller be the parent > >> of the USB host/device-controllers makes sense. For some context, I'm > >> working on adding dual-role support for Tegra210, specifically on a > >> system with USB Type-C. On Tegra, the USB host-controller and USB > >> device-controller are two separate IP blocks (XUSB host and XUSB > >> device) with another, separate, IP block (XUSB padctl) for the USB PHY > >> and OTG support. In the non-Type-C case, your OTG framework could > >> work well, though it's debatable as to whether or not the XUSB padctl > >> device should be a parent to the XUSB host/device-controller devices > >> (currently it isn't - it's just a PHY provider). But in the Type-C > >> case, it's an off-chip embedded controller that determines the > >> dual-role status of the Type-C port, so the above requirement doesn't > >> make sense at all. > > > > Hi Andrew, > > > > I think your problem is how to add your core driver to manage device and > > host functionality together, and once you find how (through padctl/type-c > > controller) to do it based on current code, it will be clear how to use roger > > proposal framework at that time. > > > > Most of current core drivers, we use extcon driver (through gpio) or USB > > vbus/id pin (through internal registers) to manager roles. > > Right, currently I'm modeling the Type-C controller as an extcon > device and handle the role-changes in the core drivers, but that > doesn't really make sense for the non-Type-C case where we use the > XUSB padctl controller and need a full OTG state-machine. The full OTG FSM is only applied if your board needs it, you can disable it through dts. Jun [1] and Roger's patchset are for it. > Roger's new > OTG/DRD framework would fit my situation perfectly since it makes the > host/device-controller drivers independent from all the > OTG/role-changing logic. The only issue is the requirement that the > OTG/DRD controller be the parent device of the host/device > controllers. > The core device is the parent for host/device device, the OTG core just use the pointer of it, Roger does an example using dwc3 [2]. [1] http://www.spinics.net/lists/linux-usb/msg127110.html [2] http://www.spinics.net/lists/linux-usb/msg126999.html -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
