From: Linus Walleij <linus.walleij@linaro.org>
To: Johan Hovold <johan@kernel.org>
Cc: Manivannan Sadhasivam <mani@kernel.org>,
Greg KH <gregkh@linuxfoundation.org>,
linux-usb <linux-usb@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
patong.mxl@gmail.com,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>
Subject: Re: [PATCH 2/2] usb: serial: xr_serial: Add gpiochip support
Date: Mon, 25 May 2020 10:59:59 +0200 [thread overview]
Message-ID: <CACRpkdapMuMs_mEUHheGtaKYg97=nL1bH3zq4Tc3cnX9Jbw-Ew@mail.gmail.com> (raw)
In-Reply-To: <20200519085703.GB27787@localhost>
On Tue, May 19, 2020 at 10:57 AM Johan Hovold <johan@kernel.org> wrote:
> > On Wed, Apr 29, 2020 at 02:12:24PM +0200, Linus Walleij wrote:
> > > 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.
>
> I think we've had this discussion before. First, not every device has a
> unique serial number. Second, we already have a universal way of
> distinguishing devices namely by using the bus topology. That's
> available through sysfs and shouldn't have to be be re-encoded by every
> driver in the gpiochip name.
I remember I even referred to this myself, but I've been waning a bit
on it recently, because it turns out that userspace/users aren't very
good at parsing sysfs for topology.
For userspace other than udev there seems to be a kind of agreement
gap. Dunno how best to bridge it though. Education maybe.
Yours,
Linus Walleij
next prev parent reply other threads:[~2020-05-25 9:00 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 19:56 [PATCH 0/2] Add support for MaxLinear/Exar USB to serial converters mani
2020-04-28 19:56 ` [PATCH 1/2] usb: serial: Add MaxLinear/Exar USB to Serial driver mani
2020-04-29 7:20 ` Greg KH
2020-04-29 7:40 ` Manivannan Sadhasivam
2020-04-29 9:29 ` Greg KH
2020-04-29 13:01 ` Manivannan Sadhasivam
2020-04-28 19:56 ` [PATCH 2/2] usb: serial: xr_serial: Add gpiochip support mani
2020-04-29 12:12 ` Linus Walleij
2020-04-29 12:49 ` Manivannan Sadhasivam
2020-05-19 8:57 ` Johan Hovold
2020-05-25 8:59 ` Linus Walleij [this message]
2020-05-25 11:12 ` Greg KH
2020-05-25 13:02 ` Linus Walleij
2020-05-25 13:35 ` Greg KH
2020-04-29 17:47 ` Manivannan Sadhasivam
2020-04-29 17:59 ` Greg KH
2020-05-19 9:08 ` Johan Hovold
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