From: Tao Ren <rentao.bupt@gmail.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Felipe Balbi <balbi@kernel.org>,
linux-aspeed@lists.ozlabs.org, devicetree@vger.kernel.org,
Andrew Jeffery <andrew@aj.id.au>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
openbmc@lists.ozlabs.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, Stephen Boyd <swboyd@chromium.org>,
Rob Herring <robh+dt@kernel.org>, Joel Stanley <joel@jms.id.au>,
taoren@fb.com, Chunfeng Yun <chunfeng.yun@mediatek.com>,
Colin Ian King <colin.king@canonical.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 7/7] dt-bindings: usb: add documentation for aspeed usb-vhub
Date: Fri, 28 Feb 2020 00:13:11 -0800 [thread overview]
Message-ID: <20200228081309.GA4531@taoren-ubuntuvm> (raw)
In-Reply-To: <2676013663fc8c53e02a5fdaafb1b27e18249b80.camel@kernel.crashing.org>
On Fri, Feb 28, 2020 at 02:02:28PM +1100, Benjamin Herrenschmidt wrote:
> On Thu, 2020-02-27 at 17:05 -0800, Tao Ren wrote:
> > > Also long run I think best is going to have a child node per downstream
> > > port, so we create a matching linux struct device. This will make it
> > > easier to deal with the other device-controller in the ast2600 which is
> > > basically one of these without a vhub above it.
> >
> > Maybe a dumb question: what would be the proper place to parse the child
> > node/properties when they are added? For example, in some usb_gadget_ops
> > callback?
>
> No. What the vhub would do is when it probes, it creates a platform
> device for each "port" child node that's linked to the DT node.
>
> The driver for the device then attaches to it via standard DT matching
> and checks if it has a vhub parent or not, and based on that, operates
> as a vhub child device or a standalone one.
>
> (For example, it might have different functions for EP selection since
> standalone devices have private EPs rather than a shared pool)
>
> They can both be in the same module or they can be separate modules
> with cross dependencies.
>
> Cheers,
> Ben.
I see. It's to describe these downstream devices (such as configurations
and according functions) in device tree, which is similar to defining a
composite device and linking functions/interfaces via configfs. Thanks for
the clarify.
Cheers,
Tao
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next prev parent reply other threads:[~2020-02-28 8:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-27 23:05 [PATCH v5 0/7] aspeed-g6: enable usb support rentao.bupt
2020-02-27 23:05 ` [PATCH v5 1/7] usb: gadget: aspeed: support per-vhub usb descriptors rentao.bupt
2020-02-27 23:05 ` [PATCH v5 2/7] usb: gadget: aspeed: read vhub properties from device tree rentao.bupt
2020-02-27 23:05 ` [PATCH v5 3/7] usb: gadget: aspeed: add ast2600 vhub support rentao.bupt
2020-02-27 23:05 ` [PATCH v5 4/7] ARM: dts: aspeed-g6: add usb functions rentao.bupt
2020-02-27 23:05 ` [PATCH v5 5/7] ARM: dts: aspeed-g5: add vhub port and endpoint properties rentao.bupt
2020-02-27 23:05 ` [PATCH v5 6/7] ARM: dts: aspeed-g4: " rentao.bupt
2020-02-27 23:05 ` [PATCH v5 7/7] dt-bindings: usb: add documentation for aspeed usb-vhub rentao.bupt
2020-02-27 23:30 ` Benjamin Herrenschmidt
2020-02-28 1:05 ` Tao Ren
2020-02-28 3:02 ` Benjamin Herrenschmidt
2020-02-28 8:13 ` Tao Ren [this message]
2020-03-02 4:49 ` Benjamin Herrenschmidt
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