On Wed, Jan 11, 2017 at 10:06:38PM +0100, Maxime Ripard wrote: > On Wed, Jan 11, 2017 at 02:08:11PM -0600, Bin Liu wrote: > > On Thu, Jan 12, 2017 at 03:55:33AM +0800, Icenowy Zheng wrote: > > > > > > > > > 11.01.2017, 04:24, "Bin Liu" <b-liu@xxxxxx>: > > > > On Tue, Jan 03, 2017 at 11:25:34PM +0800, Icenowy Zheng wrote: > > > >> Lichee Pi Zero features a USB OTG port. > > > >> > > > >> Add support for it. > > > >> > > > >> Note: in order to use the Host mode, the board must be powered via the > > > >> +5V and GND pins. > > > >> > > > >> Signed-off-by: Icenowy Zheng <icenowy@xxxxxxxx> > > > >> --- > > > >> arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts | 10 ++++++++++ > > > >> 1 file changed, 10 insertions(+) > > > >> > > > >> diff --git a/arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts b/arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts > > > >> index 0099affc6ce3..3d9168cbaeca 100644 > > > >> --- a/arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts > > > >> +++ b/arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts > > > >> @@ -71,3 +71,13 @@ > > > >> pinctrl-names = "default"; > > > >> status = "okay"; > > > >> }; > > > >> + > > > >> +&usb_otg { > > > >> + dr_mode = "otg"; > > > > > > > > Why not set this default mode in dtsi instead? > > > > > > > > Regards, > > > > -Bin. > > > > > > There's possibly boards which do not have OTG functions. > > > > That is board specific. > > Exactly, and this is why it should be done in the board DT. I am just suggesting based on the common practice. If a .dtsi exists for a family, the .dtsi describes the device and common properties for all possible boards, and each board .dts adds or overrides its specific implementation. Kernel has many devices/boards done in this way - define the default dr_mode in .dtsi. In this case, I suggest to set the common dr_mode in .dtsi, then each board .dts only overrides it if the implementation is different. > > The controller in the Allwinner SoCs do not handle directly the ID pin > and VBUS, but rather rely on a GPIO to do so. > > So boards with OTG will need setup anyway, at least to tell which > GPIOs are used. There's no point in enforcing a default if it doesn't > work by default. Then define a default which supposes to work for most boards. Why I suggest this, is because defining a default dr_mode which works for most cases in dtsi could prevent a little surprise in MUSB function. If someone designs a new board but forgets to define dr_mode in the new board DT, the MUSB driver will default to org mode, which might not be intended. Regards, -Bin. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html