On 22/01/15 15:32, Roger Quadros wrote: > Felipe, > > On 20/01/15 21:02, Felipe Balbi wrote: >> On Mon, Jan 19, 2015 at 07:52:17PM +0200, Roger Quadros wrote: >>> Hi, >>> >>> On DRA7 EVMs the USB ID pin is connected to a GPIO line. The USB drivers >>> (dwc3 + dwc3-omap) depend on extcon framework to get the USB cable state >>> (USB or USB-Host) to put the controller in the right mode. >>> >>> There were earlier attempts [1] to get this working by trying to patch up >>> the existing GPIO extcon driver. >>> >>> This series attemts to take a different approach by introducing a new >>> USB specific extcon driver to handle the USB ID GPIO pin and >>> interpret a right USB cable state. >>> >>> The reasoning to introduce this new driver is: >>> 1) The existing GPIO extcon driver doesn't understand USB cable states >>> and it can't handle more than one cable per instance. >>> >>> For the USB case we need to handle at least 2 cable states. >>> a) USB (attach/detach) >>> b) USB-Host (attach/detach) >>> and could possible include more states like >>> c) Fast-charger (attach/detach) >>> d) Slow-charger (attach/detach) >>> >>> 2) This USB specific driver can be easily updated in the future to >>> handle VBUS events, or charger detect events, in case it happens >>> to be available on GPIO for any platform. >>> >>> 3) The DT implementation is very easy. You just need one extcon node per USB >>> instead of one extcon node per cable state as in case of [1]. >>> >>> 4) The cable state string doesn't need to be encoded in the device tree >>> as in case of [1]. >>> >>> 5) With only ID event available, you can simulate a USB-peripheral attach >>> when USB-Host is detacted instead of hacking the USB driver to do the same. >>> >>> Tested on DRA7-evm and DRA72-evm. >> >> while at that, you might want to patch X15 too. >> > USB2 port is meant for peripheral use only. ID pin from USB port is not connected to GPIO. > OK answering myself here :). Peripheral mode doesn't work on x15-bb as the USB driver (dwc3-omap) doesn't set the mailbox correctly even when dwc3 node is set as otg = "peripheral". Looks like we need to implement usb-gpio-extcon for x15 even though ID is hard coded. cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
