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. 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. Thanks, Andrew -- 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
