Hi Linus and Robert, CC'ing Heikki as it involves a RFC from him. On Fri, Feb 20, 2015 at 10:53:44AM +0100, Linus Walleij wrote: > On Fri, Feb 20, 2015 at 7:41 AM, Robert Baldyga <r.baldyga@xxxxxxxxxxx> wrote: > > Hi David, > > > > On 02/19/2015 08:59 PM, David Cohen wrote: > >> Some Intel platforms have an USB OTG port fully (or partially) > >> controlled by GPIOs: > >> > >> (1) USB ID is connected directly to a pulled up GPIO. > >> > >> Optionally: > >> (2) VBUS is enabled/disabled by a GPIO > >> (3) Platform has 2 USB controllers connected to same port: one for > >> device and one for host role. D+/- are switched between phys. > >> according to this GPIO level. > >> > >> This driver configures USB OTG port for device or host role according to > >> USB ID value. > >> - If USB ID's GPIO level is low, OTG port is configured for host role > >> by sourcing VBUS and switching D+/- to host phy. > >> - If USB ID's GPIO level is high, by standard, the OTG port is > >> configured for device role by not sourcing VBUS and switching D+/- to > >> device controller. > > > > IMO it's not very elegant to handle VBUS power on/off in extcon driver. > > Creating fixed regulator would allow to make VBUS handling more generic. I agree. But please, see below. > > IMHO it's just layers of abstraction piled on top of each other here. > > I would put this adjacent to the phy driver somewhere in drivers/usb/* > and make the actual USB-driver thing handle its GPIOs directly. > But I guess David and Felipe have already discussed that as we're > seeing this patch? Felipe suggested to "divide to conquer" instead of having a single extcon driver to handle all these functions: - The mux functions would be controlled by a possible new pinctrl-gpio driver (Linus, your input here would be nice :) - The VBUS would be a fixed regulator - The USB ID would make usage of existent extcon-gpio But the on fw side, this is a single ACPI device representing a virtual device for USB OTG port, which is nothing but a bunch of independent GPIOs. I could make a mfd driver to register devices for those simpler and more generic drivers, but according to [1] community recognized it as a hack with ACPI since I'd need to give them the GPIO without requesting on mfd. I'm open for suggestions :) Br, David [1] https://lkml.org/lkml/2014/12/18/82 > > Yours, > Linus Walleij -- 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
