From: Thierry Reding <thierry.reding@gmail.com>
To: Nagarjuna Kristam <nkristam@nvidia.com>
Cc: JC Kuo <jckuo@nvidia.com>,
balbi@kernel.org, gregkh@linuxfoundation.org,
jonathanh@nvidia.com, mark.rutland@arm.com, robh+dt@kernel.org,
kishon@ti.com, devicetree@vger.kernel.org,
linux-tegra@vger.kernel.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [Patch V2 01/18] dt-bindings: phy: tegra-xusb: Add usb-role-switch
Date: Mon, 13 Jan 2020 16:06:56 +0100 [thread overview]
Message-ID: <20200113150656.GB2436168@ulmo> (raw)
In-Reply-To: <6eb31a50-472f-439c-3bc7-bcad1c0c9ff4@nvidia.com>
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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@nvidia.com>
> > > > > ---
> > > > > 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@nvidia.com>
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next prev parent reply other threads:[~2020-01-13 15:07 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 9:16 [Patch V2 00/18] Tegra XUSB OTG support Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 01/18] dt-bindings: phy: tegra-xusb: Add usb-role-switch Nagarjuna Kristam
2019-12-19 13:05 ` Thierry Reding
2019-12-20 8:08 ` JC Kuo
2020-01-10 11:16 ` Thierry Reding
2020-01-13 4:37 ` Nagarjuna Kristam
2020-01-13 15:06 ` Thierry Reding [this message]
2019-12-18 9:16 ` [Patch V2 02/18] dt-bindings: usb: Add NVIDIA Tegra XUSB device mode controller binding Nagarjuna Kristam
2019-12-18 23:24 ` Rob Herring
2019-12-19 13:10 ` Thierry Reding
2019-12-18 9:16 ` [Patch V2 03/18] phy: tegra: xusb: Add usb-role-switch support Nagarjuna Kristam
2019-12-19 13:26 ` Thierry Reding
2019-12-27 6:39 ` Nagarjuna Kristam
2019-12-29 9:36 ` Thierry Reding
2019-12-30 5:17 ` Nagarjuna Kristam
2019-12-26 6:42 ` JC Kuo
2019-12-27 6:18 ` Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 04/18] phy: tegra: xusb: Add usb-phy support Nagarjuna Kristam
2019-12-19 13:37 ` Thierry Reding
2019-12-27 7:06 ` Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 05/18] phy: tegra: xusb: Add support to get companion USB 3 port Nagarjuna Kristam
2019-12-26 7:03 ` JC Kuo
2019-12-18 9:16 ` [Patch V2 06/18] phy: tegra: xusb: Add set_mode support for USB 2 phy on Tegra210 Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 07/18] phy: tegra: xusb: Add set_mode support for utmi phy on Tegra186 Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 08/18] usb: xhci-tegra: Add OTG support Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 09/18] usb: gadget: tegra-xudc: Remove usb-role-switch support Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 10/18] usb: gadget: tegra-xudc: Add usb-phy support Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 11/18] usb: gadget: tegra-xudc: use phy_set_mode to set/unset device mode Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 12/18] usb: gadget: tegra-xudc: support multiple device modes Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 13/18] arm64: tegra: update OTG port entries for jetson-tx1 Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 14/18] arm64: tegra: update OTG port entries for jetson-tx2 Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 15/18] arm64: tegra: Add xudc node for Tegra210 Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 16/18] arm64: tegra: Enable xudc on Jetson TX1 Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 17/18] arm64: tegra: Add xudc node for Tegra186 Nagarjuna Kristam
2019-12-18 9:16 ` [Patch V2 18/18] arm64: tegra: Enable xudc node on Jetson TX2 Nagarjuna Kristam
2019-12-19 13:13 ` [Patch V2 00/18] Tegra XUSB OTG support Thierry Reding
2019-12-20 7:35 ` JC Kuo
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