linux-kernel - Re: [PATCH 2/2] usb: serial: xr

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Message-ID: <CACRpkdZ3b-VLvxN06H_4cDOtUEQTVbe=Zw+NA=YjssMzK2d2sQ@mail.gmail.com>
Date:   Wed, 29 Apr 2020 14:12:24 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     mani@...nel.org
Cc:     Johan Hovold <johan@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        linux-usb <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        patong.mxl@...il.com,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 2/2] usb: serial: xr_serial: Add gpiochip support

On Tue, Apr 28, 2020 at 9:57 PM <mani@...nel.org> wrote:

> From: Manivannan Sadhasivam <mani@...nel.org>
>
> Add gpiochip support for Maxlinear/Exar USB to serial converter
> for controlling the available gpios.
>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Cc: linux-gpio@...r.kernel.org
> Signed-off-by: Manivannan Sadhasivam <mani@...nel.org>

That's a nice and clean GPIO driver.

I would change this:

   port_priv->gc.label = "xr_gpios";

to something that is device-unique, like "xr-gpios-<serial number>"
which makes it easy to locate the GPIOs on a specific serial converter
for lab use. However the USB serial maintainers know better what
to use here. Whatever makes a USB-to-serial unique from a TTY
point of view is probably fine with me too.

My idea is that people might want to know which USB cable
this is sitting on, so I have this USB cable and from this label
I can always figure out which GPIO device it is.

Either way, it is not a super-big issue so:
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Is this a off-the-shelf product that can be bought or is it mainly
integrated on boards?

I'm asking because I'm looking for a neat USB-to-serial adapter
with some GPIOs (2 is enough) that can be used for reset and
power cycling of lab boards using one simple piece of equipment.

Yours,
Linus Walleij