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. -- balbi
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