On Fri, Feb 20, 2015 at 01:36:06PM -0600, Felipe Balbi wrote: > On Fri, Feb 20, 2015 at 11:17:00AM -0800, David Cohen wrote: > > 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 :) > > use MFD to create children devices and pass the required data to each > one ? I'd need to lookup GPIOs via ACPI without requesting them on mfd driver and then give them to children devices. Heikki proposed a way to do that on [1], but it got nack'ed by community. Br, David > > -- > balbi -- 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
