From: Linus Walleij <linus.walleij@linaro.org>
To: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Drew Fustini <drew@pdp7.com>,
Robert Nelson <robertcnelson@gmail.com>,
Haojian Zhuang <haojian.zhuang@linaro.org>,
Santosh Shilimkar <ssantosh@kernel.org>,
Kevin Hilman <khilman@kernel.org>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
Jason Kridner <jkridner@beagleboard.org>,
Tony Lindgren <tony@atomide.com>,
linux-omap <linux-omap@vger.kernel.org>,
Kent Gibson <warthog618@gmail.com>,
Bartosz Golaszewski <brgl@bgdev.pl>
Subject: Re: gpio-omap: add support gpiolib bias (pull-up/down) flags?
Date: Fri, 17 Apr 2020 12:37:45 +0200 [thread overview]
Message-ID: <CACRpkdZww1k-vo32FRjQZ0Qic_FccHh4KuekNm1aU3i5XW6Gog@mail.gmail.com> (raw)
In-Reply-To: <495f118d-380d-a994-d8f9-bacdfe4efb85@ti.com>
On Thu, Apr 16, 2020 at 4:17 PM Grygorii Strashko
<grygorii.strashko@ti.com> wrote:
> (Changing MUX_MODE from user space sounds very unsafe for me.)
The way it works on a lot of platforms is to implement the
gpio_request_enable() callback such that it muxes the pin
when requested to use as GPIO.
How to handle that is up to the driver, but the simple ones
just assume that if (A) the pin is not muxed for something
else like SPI or MMC or whatever and (B) the pin can be
muxed into GPIO mode, then it goes ahead and does that.
But this policy is up to the driver maintainer.
Given that Beagles etc are pretty much for makers and
industrial control and such, a relaxed policy would be
beneficial for users that want to do some tinkerytink.
The reverse goes for users making airplane control
systems.
Yours,
Linus Walleij
next prev parent reply other threads:[~2020-04-17 10:38 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-08 13:08 gpio-omap: add support gpiolib bias (pull-up/down) flags? Drew Fustini
2020-03-12 10:43 ` Linus Walleij
2020-03-13 0:39 ` Drew Fustini
2020-03-13 5:23 ` Haojian Zhuang
2020-04-13 12:39 ` Drew Fustini
2020-04-15 13:15 ` Grygorii Strashko
2020-04-15 13:20 ` Robert Nelson
2020-04-15 13:47 ` Grygorii Strashko
2020-04-15 13:59 ` Robert Nelson
2020-04-15 23:37 ` Drew Fustini
2020-04-16 12:03 ` Linus Walleij
2020-04-16 16:07 ` Drew Fustini
2020-04-16 14:16 ` Grygorii Strashko
2020-04-17 10:37 ` Linus Walleij [this message]
2020-04-16 16:32 ` Tony Lindgren
2020-04-23 13:17 ` Drew Fustini
2020-04-23 16:42 ` Tony Lindgren
2020-04-24 17:32 ` Drew Fustini
2020-04-24 17:49 ` Tony Lindgren
2020-05-25 13:17 ` Drew Fustini
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