On Mon, Jan 13, 2020 at 10:07:08AM +0530, Nagarjuna Kristam wrote: > > On 10-01-2020 16:46, Thierry Reding wrote: > > On Fri, Dec 20, 2019 at 04:08:30PM +0800, JC Kuo wrote: > > > On 12/19/19 9:05 PM, Thierry Reding wrote: > > > > On Wed, Dec 18, 2019 at 02:46:14PM +0530, Nagarjuna Kristam wrote: > > > > > Add usb-role-switch property for Tegra210 and Tegra186 platforms. This > > > > > entry is used by XUSB pad controller driver to register for role changes > > > > > for OTG/Peripheral capable USB 2 ports. > > > > > > > > > > Signed-off-by: Nagarjuna Kristam<nkristam@xxxxxxxxxx> > > > > > --- > > > > > V2: > > > > > - Moved usb-role-switch to seperate Required section as suggested by Thierry. > > > > > - Added reference to usb/usb-conn-gpio.txt for connector subnode. > > > > > --- > > > > > .../devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt | 6 ++++++ > > > > > 1 file changed, 6 insertions(+) > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt b/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt > > > > > index 9fb682e..23bf354 100644 > > > > > --- a/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt > > > > > +++ b/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt > > > > > @@ -174,6 +174,12 @@ Required properties: > > > > > - "device": for USB device mode > > > > > - "otg": for USB OTG mode > > > > > +Required properties for OTG/Peripheral capable USB2 ports: > > > > > +- usb-role-switch: Boolean property to indicate that the port support OTG or > > > > "supports", and also, why if it supports OTG*or* peripheral? Doesn't > > > > OTG imply peripheral? OTG means it can be either peripheral or host, > > > > right? So I think the end of that sentence can be just: > > > > > > > > "... the port supports OTG." > > > An USB OTG port is capable of both USB host and peripheral operations. An USB > > > peripheral port can only act as an USB peripheral. > > > > > > The micro USB ports found on Jetson TX1/TX2 platforms are micro-AB ports which > > > should implement both host and peripheral capabilities. We say such ports > > > support OTG. The micro USB port found on Jetson Nano is a micro-B port which > > > should implement peripheral capability only. We say such ports support > > > peripheral, rather than OTG. > > I the port supports only peripheral mode, why do we need to have a > > usb-role-switch property? Shouldn't we in that case have a mode property > > with value "device"? > > > > usb-mode-switch is only needed if mode = "otg", isn't it? In all other > > cases the functionality is fixed (either host or peripheral) and the > > mode cannot be switched. > > > > Thierry > > usb-role-switch is needed when mode == "otg" or "peripheral". > > Device mode is detected via vbus GPIO irrespective of mode being peripheral > only or OTG. > Host mode is detected via id-gpio, in OTG case. > > When mode is peripheral, role changes happens between USB_ROLE_DEVICE and > USB_ROLE_NONE, which are generally based on Vbus GPIO(hot plug) detection. > > When mode is otg, role changes happens between USB_ROLE_HOST, > USB_ROLE_DEVICE and USB_ROLE_NONE, which are detected via id-gpio, vbus-gpio > and no detection respectively. Right, that makes perfect sense. Thanks for putting it so clearly. With the "support" -> "supports" typo fixed, this patch: Acked-by: Thierry Reding <treding@xxxxxxxxxx>
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