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From: Linus Walleij <linus.walleij@linaro.org>
To: Marc Zyngier <maz@kernel.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: 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>,
	Johan Hovold <johan@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	kernel-team@android.com
Subject: Re: [PATCH 1/4] gpiolib: cdev: Flag invalid GPIOs as used
Date: Wed, 9 Dec 2020 10:25:01 +0100	[thread overview]
Message-ID: <CACRpkdb6AH6RGDenAXTofwTRvZcJp1cg6gXxC26MuXL7EPDtwg@mail.gmail.com> (raw)
In-Reply-To: <20201204164739.781812-2-maz@kernel.org>

On Fri, Dec 4, 2020 at 5:47 PM Marc Zyngier <maz@kernel.org> wrote:

> When reporting the state of a GPIO to userspace, we never check
> for the actual validity of the line, meaning we report invalid
> lines as being usable. A subsequent request will fail though,
> which is an inconsistent behaviour from a userspace perspective.
>
> Instead, let's check for the validity of the line and report it
> as used if it is invalid. This allows a tool such as gpioinfo
> to report something sensible:
>
> gpiochip3 - 4 lines:
>         line   0:      unnamed       unused   input  active-high
>         line   1:      unnamed       kernel   input  active-high [used]
>         line   2:      unnamed       kernel   input  active-high [used]
>         line   3:      unnamed       unused   input  active-high
>
> In this example, lines 1 and 2 are invalid, and cannot be used by
> userspace.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>

This makes sense, so patch applied (unless Bartosz tells me
otherwise, then I'll pull it out again).

Yours,
Linus Walleij

  parent reply	other threads:[~2020-12-09  9:26 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 [this message]
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
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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