From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [Patch V2 01/18] dt-bindings: phy: tegra-xusb: Add usb-role-switch Date: Fri, 10 Jan 2020 12:16:33 +0100 Message-ID: <20200110111633.GA2233456@ulmo> References: <1576660591-10383-1-git-send-email-nkristam@nvidia.com> <1576660591-10383-2-git-send-email-nkristam@nvidia.com> <20191219130503.GG1440537@ulmo> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="uAKRQypu60I7Lcqm" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: JC Kuo Cc: Nagarjuna Kristam , balbi-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, kishon-l0cyMroinI0@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org --uAKRQypu60I7Lcqm Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Dec 20, 2019 at 04:08:30PM +0800, JC Kuo wrote: >=20 > 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 chang= es > >> for OTG/Peripheral capable USB 2 ports. > >> > >> Signed-off-by: Nagarjuna Kristam > >> --- > >> 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-xus= b-padctl.txt b/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-p= adctl.txt > >> index 9fb682e..23bf354 100644 > >> --- a/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padct= l.txt > >> +++ b/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padct= l.txt > >> @@ -174,6 +174,12 @@ Required properties: > >> - "device": for USB device mode > >> - "otg": for USB OTG mode > >> =20 > >> +Required properties for OTG/Peripheral capable USB2 ports: > >> +- usb-role-switch: Boolean property to indicate that the port support= OTG or > >=20 > > "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: > >=20 > > "... 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. >=20 > 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 wh= ich > 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 =3D "otg", isn't it? In all other cases the functionality is fixed (either host or peripheral) and the mode cannot be switched. Thierry --uAKRQypu60I7Lcqm Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAl4YXREACgkQ3SOs138+ s6GSDA//Yw+iQiAYCgTYvc8Y87l6JkMSfV5RQCKnFtHwPuevL/EIVxztqcP6eia0 ejTKfTSjVgF03rW7wGevtgY/g/xrn2K0IcaIYOwFqNZiOKY7lCcGjvuqOKbg+jsz TKJJR+Y3NTyGHYHmsv9vGjqpLgIzIWNaRc6Ena5HoZZ0o0CW8TmLTynK2a6mG/OO k7WT6fbFB6eGykl/KlnCghg5p/tgLwRFNhPI9I6eOO6w2BNvKhOqPc1isblZdQ1v Ct4XyitxtqdCSvHtO8X3B7aNDtgn/n9ch2Gu5Ws1Y3ZK94iNFK8x29RV9Z+DoHbb 253u4npM88dzRNj2UOT9Q3RVh0E1a58RwNq3PIA9VPbzPyRo0X7eOqA5SiGGKspo zXCiEGwBonv0dK9iBNUsceDuf5eQHHBDpujLGAyvSMFKQOTVw35i2T+29Nul6XFT rJ35Dnp1wCzRA3FYGfYZMfDHTQJzFFhy4pPvOCU5wqv+Oi1BThLjrWcVHoQWvUCr 0lH/1ceX0A+c0bRMmRVZxZCCEk0xz5oafmFcp89oGwX1rQxtfh4uxeU6VrihTl3O Yvyk9Rx5HxcZ0zyytaE5NdVlKOdQKuRS7w+ayeX6iVKN3453YLO+oWVZ0DQc/IKJ eiN/eOfcl2ZckowJ5ITjilaL35vwRe95RYVtTS1YRgqfe1Gz+4Y= =8Zk5 -----END PGP SIGNATURE----- --uAKRQypu60I7Lcqm--