linux-kernel - Re: [PATCH 4/4] ARM: dts: sun8i: add OTG function to Lichee Pi Zero

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Message-ID: <20170111203326.GB16865@uda0271908>
Date:   Wed, 11 Jan 2017 14:33:26 -0600
From:   Bin Liu <b-liu@...com>
To:     Icenowy Zheng <icenowy@...c.xyz>
CC:     Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Kishon Vijay Abraham I <kishon@...com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 4/4] ARM: dts: sun8i: add OTG function to Lichee Pi Zero

On Thu, Jan 12, 2017 at 04:13:34AM +0800, Icenowy Zheng wrote:
> 
> 
> 12.01.2017, 04:08, "Bin Liu" <b-liu@...com>:
> > On Thu, Jan 12, 2017 at 03:55:33AM +0800, Icenowy Zheng wrote:
> >>  11.01.2017, 04:24, "Bin Liu" <b-liu@...com>:
> >>  > 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@...c.xyz>
> >>  >>  ---
> >>  >>   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.
> >
> > You'd better to define the default dr_mode which the musb _controller_
> > supports in the dtsi, and then override it in a specific board dts if
> > necessary.
> 
> Is there MUSB controllers which do not support a certain mode?

I am not aware of any. That is why I recommended to set "otg" in dtsi,
then override it in board dts if a port is specically designed to
host-only or device-only mode.

> 
> (I remembered my omap3-n900 which do not work under OTG mode...)

I belive it is n900 board specific. omap3 itself doesn't have such
limitation, AFAIK.

Regards,
-Bin.

> 
> >
> > Regards,
> > -Bin.
> >
> >>  Even the official CDR design of V3s uses the USB controller to
> >>  connect a UVC webcam to make the design a dual-cam design
> >>  (V3s itself has a CSI).
> >>
> >>  >
> >>  >>  + status = "okay";
> >>  >>  +};
> >>  >>  +
> >>  >>  +&usbphy {
> >>  >>  + usb0_id_det-gpio = <&pio 5 6 GPIO_ACTIVE_HIGH>;
> >>  >>  + status = "okay";
> >>  >>  +};
> >>  >>  --
> >>  >>  2.11.0