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From: Linus Walleij <linus.walleij@linaro.org>
To: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Cc: "brgl@bgdev.pl" <brgl@bgdev.pl>,
	"johan@kernel.org" <johan@kernel.org>,
	"andy.shevchenko@gmail.com" <andy.shevchenko@gmail.com>,
	"maz@kernel.org" <maz@kernel.org>,
	Ben Brown <Ben.Brown@alliedtelesis.co.nz>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] gpiolib: Avoid side effects in gpio_is_visible()
Date: Tue, 16 May 2023 15:57:57 +0200	[thread overview]
Message-ID: <CACRpkdbiSAFoJP_JB1d_6gQ+Xx7Y+mLAh=C6Za+fpyWuRe6Gbw@mail.gmail.com> (raw)
In-Reply-To: <b36fcdf1-45ab-0c06-efe4-237df0612466@alliedtelesis.co.nz>

On Mon, May 15, 2023 at 12:27 AM Chris Packham
<Chris.Packham@alliedtelesis.co.nz> wrote:

> In my original case which is a kernel module that exports a GPIO for
> userspace using gpiod_export()

We should not add new users for that API as it increase the usage
of the sysfs ABI but if it's an existing in-tree usecase I buy it.

> The crux of the problem is that the irq_desc is created when it hasn't
> been requested.

The right solution to me seems to be to not use gpiod_export()
and not use sysfs TBH.

> In some cases we know the GPIO pin is an output so we
> could avoid it, in others we could delay the creation until an interrupt
> is actually requested (which is what I'm attempting to do).

Yeah I guess. If we wanna keep papering over issues created
by the sysfs ABI.

Yours,
Linus Walleij

  reply	other threads:[~2023-05-16 13:58 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-12  4:28 [PATCH] gpiolib: Avoid side effects in gpio_is_visible() Chris Packham
2023-05-12  7:24 ` Johan Hovold
2023-05-14 21:57   ` Chris Packham
2023-05-15  6:43     ` andy.shevchenko
2023-05-15 21:01       ` Chris Packham
2023-05-12  7:56 ` Linus Walleij
2023-05-14 22:27   ` Chris Packham
2023-05-16 13:57     ` Linus Walleij [this message]
2023-05-16 22:19       ` Chris Packham
2023-05-16 22:47         ` Kent Gibson
2023-05-16 23:50           ` Chris Packham
2023-05-17  0:47             ` Kent Gibson
2023-05-17  1:05               ` Kent Gibson
2023-05-17  1:07               ` Chris Packham
2023-05-17  1:21                 ` Kent Gibson
2023-05-17  8:54             ` Andy Shevchenko
2023-05-17  9:10               ` Kent Gibson
2023-05-17 21:30               ` Chris Packham
2023-05-23 16:38                 ` andy.shevchenko
2023-05-23 21:17                   ` Chris Packham
2023-05-24  5:41                     ` Kent Gibson
2023-05-24 23:53                       ` using libgpiod to replace sysfs ABI (was Re: [PATCH] gpiolib: Avoid side effects in gpio_is_visible()) Chris Packham
2023-05-25  1:19                         ` Kent Gibson
2023-05-25  9:13                         ` Andy Shevchenko
2023-05-25 14:35                           ` Bartosz Golaszewski
2023-05-26 12:46                       ` [PATCH] gpiolib: Avoid side effects in gpio_is_visible() Bartosz Golaszewski
2023-05-28 21:04                         ` Chris Packham
2023-05-29  9:19                 ` Linus Walleij
2023-05-29 15:07                   ` Andrew Lunn
2023-05-29  9:07         ` Linus Walleij
2023-05-29 22:00           ` Chris Packham

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