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. cheers, -roger -- 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
