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From: Thierry Reding <thierry.reding@gmail.com>
To: JC Kuo <jckuo@nvidia.com>
Cc: Nagarjuna Kristam <nkristam@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: Fri, 10 Jan 2020 12:16:33 +0100	[thread overview]
Message-ID: <20200110111633.GA2233456@ulmo> (raw)
In-Reply-To: <fe47fd52-efd0-4f84-d1e4-4bce5571e425@nvidia.com>

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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

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  reply	other threads:[~2020-01-10 11:16 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 [this message]
2020-01-13  4:37         ` Nagarjuna Kristam
2020-01-13 15:06           ` Thierry Reding
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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