On Fri, Jan 23, 2015 at 09:26:56AM +0200, Roger Quadros wrote: > 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. yeah, let's implement that for 3.21. -- balbi
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