Felipe, On 22/01/15 22:29, Felipe Balbi wrote: > On Thu, Jan 22, 2015 at 04:57:56PM +0200, Roger Quadros wrote: >> >> 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. > > right, another option is to have dwc3-omap read the child's DTS to check > dr_mode and hardcode things based on that. > I think that option is better as it doesn't require a GPIO line to be reserved for ID when USB is not meant for dual-role use.
cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
