From: Alan Stern <stern@rowland.harvard.edu>
To: Matthias Kaehlcke <mka@chromium.org>
Cc: Doug Anderson <dianders@chromium.org>,
Rob Herring <robh@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Frank Rowand <frowand.list@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linux USB List <linux-usb@vger.kernel.org>,
Bastien Nocera <hadess@hadess.net>,
Stephen Boyd <swboyd@chromium.org>,
Ravi Chandra Sadineni <ravisadineni@chromium.org>,
Krzysztof Kozlowski <krzk@kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>, Peter Chen <peter.chen@nxp.com>
Subject: Re: [PATCH v4 1/2] dt-bindings: usb: Add binding for discrete onboard USB hubs
Date: Tue, 6 Oct 2020 10:18:20 -0400 [thread overview]
Message-ID: <20201006141820.GA416765@rowland.harvard.edu> (raw)
In-Reply-To: <20201006004510.GD4135817@google.com>
On Mon, Oct 05, 2020 at 05:45:10PM -0700, Matthias Kaehlcke wrote:
> I did some prototyping, it seems a binding like this would work for
> case a) or b):
>
> &usb_1_dwc3 {
> hub_2_0: hub@1 {
> compatible = "usbbda,5411";
> reg = <1>;
> };
>
> hub_3_0: hub@2 {
> compatible = "usbbda,411";
> reg = <2>;
> vdd-supply = <&pp3300_hub>;
> companion-hubs = <&hub_2_0>;
> };
> };
>
> It still requires specifying both hubs (which reflects the actual wiring).
> Supporting something like "reg = <1 2>" seems more complex due to the need to
> obtain the hub USB device at runtime (a DT node makes that trivial), possibly
> this could be solved by adding new APIs.
>
> In terms of implementation would I envision to keep a platform driver. This
> would keep the hubby parts out of xhci-plat (except for populating the platform
> devices), support systems with cascaded hubs and provide a device for the sysfs
> attribute.
What will you do if a system has more than one of these power-regulated
hubs? That is, how will the user know which platform device handles the
power control for a particular hub (and vice versa)? You'd probably
have to create a pair of symlinks going back and forth in the sysfs
directories.
Wouldn't it be easier to put the power-control attribute directly in the
hub's sysfs directory (or .../power subdirectory)?
Alan Stern
next prev parent reply other threads:[~2020-10-06 14:18 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-28 17:13 [PATCH v4 1/2] dt-bindings: usb: Add binding for discrete onboard USB hubs Matthias Kaehlcke
2020-09-28 17:13 ` [PATCH v4 2/2] USB: misc: Add onboard_usb_hub driver Matthias Kaehlcke
2020-09-28 18:47 ` Alan Stern
2020-09-29 1:43 ` Matthias Kaehlcke
2020-09-29 16:00 ` Alan Stern
2020-09-29 16:50 ` Matthias Kaehlcke
2020-09-28 22:03 ` Doug Anderson
2020-09-29 1:59 ` Matthias Kaehlcke
2020-09-28 22:13 ` [PATCH v4 1/2] dt-bindings: usb: Add binding for discrete onboard USB hubs Doug Anderson
2020-09-29 2:14 ` Matthias Kaehlcke
2020-09-29 20:17 ` Rob Herring
2020-09-29 22:09 ` Matthias Kaehlcke
2020-09-30 1:32 ` Alan Stern
2020-09-30 12:49 ` Matthias Kaehlcke
2020-09-30 14:44 ` Rob Herring
2020-09-30 15:28 ` Doug Anderson
2020-09-30 18:00 ` Doug Anderson
2020-09-30 19:19 ` Rob Herring
2020-10-01 21:39 ` Matthias Kaehlcke
2020-09-30 19:19 ` Alan Stern
2020-09-30 20:20 ` Rob Herring
2020-10-01 1:24 ` Alan Stern
2020-10-01 21:54 ` Matthias Kaehlcke
2020-10-02 1:21 ` Alan Stern
2020-10-02 16:08 ` Matthias Kaehlcke
2020-10-02 18:48 ` Alan Stern
2020-10-02 17:08 ` Doug Anderson
2020-10-02 18:36 ` Alan Stern
2020-10-02 22:58 ` Rob Herring
2020-10-03 12:41 ` Alan Stern
2020-10-05 16:06 ` Matthias Kaehlcke
2020-10-05 16:15 ` Alan Stern
2020-10-05 19:18 ` Matthias Kaehlcke
2020-10-05 19:36 ` Alan Stern
2020-10-05 19:59 ` Rob Herring
2020-10-05 23:29 ` Matthias Kaehlcke
2020-10-05 19:36 ` Rob Herring
2020-10-05 19:20 ` Rob Herring
2020-10-02 22:28 ` Rob Herring
2020-10-02 23:09 ` Doug Anderson
2020-10-06 0:45 ` Matthias Kaehlcke
2020-10-06 14:18 ` Alan Stern [this message]
2020-10-06 16:59 ` Matthias Kaehlcke
2020-10-06 17:15 ` Alan Stern
2020-10-06 19:25 ` Matthias Kaehlcke
2020-10-07 1:00 ` Alan Stern
2020-10-07 16:03 ` Matthias Kaehlcke
2020-10-07 16:38 ` Alan Stern
2020-10-07 17:28 ` Matthias Kaehlcke
2020-10-07 19:25 ` Alan Stern
2020-10-07 19:42 ` Matthias Kaehlcke
2020-10-07 20:17 ` Alan Stern
2020-10-07 21:42 ` Matthias Kaehlcke
2020-10-08 14:09 ` Alan Stern
2020-10-09 23:13 ` Matthias Kaehlcke
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