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From: Johan Hovold <johan@kernel.org>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Johan Hovold <johan@kernel.org>, Marc Zyngier <maz@kernel.org>,
	linux-usb <linux-usb@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	kernel-team@android.com
Subject: Re: [PATCH 3/4] USB: serial: ftdi_sio: Log the CBUS GPIO validity
Date: Wed, 9 Dec 2020 18:39:53 +0100	[thread overview]
Message-ID: <X9EL6SwjutCHTPO+@localhost> (raw)
In-Reply-To: <X9ED9k5gxIlQ0YJ/@localhost>

On Wed, Dec 09, 2020 at 06:05:58PM +0100, Johan Hovold wrote:
> On Wed, Dec 09, 2020 at 10:35:53AM +0100, Linus Walleij wrote:

> > It sounds like we agree that this patch sans prints is acceptable.
> > 
> > It makes things better so let's go with that.
> 
> Sounds good.
> 
> I'm about to apply patches 2, 3 and 4 with some smaller changes like
> demoting the printk messages to KERN_DEBUG and dropping the ftx-progs
> warning.
>
> > The problem for the user is that the line looks to be
> > "used by the kernel" (true in some sense) but they have no
> > idea what to do about it and that the ftx-prog will solve
> > their hacking problem.
> 
> Right, it's not ideal, but the datasheets for these devices clearly
> states that the configuration of the CBUS pins is done in EEPROM and the
> vendor provides some tool to do that. Then there's a bunch of open
> source implementations for the same including ftx-progs (which can only
> be used for a subset of these devices).
> 
> I'd be fine with a dev_err() on the first request that fails saying that
> the CBUS pin is not configured for GPIO use (perhaps even on every
> request if its not something that a non-root user can trigger). But we
> cannot have both that and have the line marked in-use through the
> chardev interface currently.
> 
> I'm admittedly a bit torn on which is preferable.

I've applied the patches now. Having this reported through the chardev
interface must be better than having to match up a failed request with
something in the system log.

Johan

  reply	other threads:[~2020-12-09 17:40 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-04 16:47 [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes Marc Zyngier
2020-12-04 16:47 ` [PATCH 1/4] gpiolib: cdev: Flag invalid GPIOs as used Marc Zyngier
2020-12-07 14:16   ` Johan Hovold
2020-12-07 14:59     ` Marc Zyngier
2020-12-09  9:25   ` Linus Walleij
2020-12-04 16:47 ` [PATCH 2/4] USB: serial: ftdi_sio: Report the valid GPIO lines to gpiolib Marc Zyngier
2020-12-09  9:28   ` Linus Walleij
2020-12-04 16:47 ` [PATCH 3/4] USB: serial: ftdi_sio: Log the CBUS GPIO validity Marc Zyngier
2020-12-07 14:29   ` Johan Hovold
2020-12-07 15:00     ` Marc Zyngier
2020-12-07 15:19       ` Johan Hovold
2020-12-09  9:35         ` Linus Walleij
2020-12-09 17:05           ` Johan Hovold
2020-12-09 17:39             ` Johan Hovold [this message]
2020-12-04 16:47 ` [PATCH 4/4] USB: serial: ftdi_sio: Drop GPIO line checking dead code Marc Zyngier
2020-12-07  9:55 ` [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes Andy Shevchenko
2020-12-07 14:01 ` Johan Hovold
2020-12-07 14:41   ` Marc Zyngier
2020-12-07 15:08     ` Johan Hovold
2020-12-07 15:34       ` Marc Zyngier
2020-12-07 15:49         ` Johan Hovold
2020-12-09  9:20           ` Linus Walleij
2020-12-09 15:42             ` Johan Hovold

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