From: Sander Vanheule <sander@svanheule.net>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>, Pavel Machek <pavel@ucw.cz>,
Rob Herring <robh+dt@kernel.org>,
Lee Jones <lee.jones@linaro.org>, Mark Brown <broonie@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Michael Walle <michael@walle.cc>,
Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Linux LED Subsystem <linux-leds@vger.kernel.org>,
devicetree <devicetree@vger.kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 0/6] RTL8231 GPIO expander support
Date: Mon, 24 May 2021 17:20:13 +0200 [thread overview]
Message-ID: <69c95adb6bafb8fbf69b9f79613606f62ba769e8.camel@svanheule.net> (raw)
In-Reply-To: <CAHp75Vf_dAfoMmziVLkEQ2Yr-e7Cj5=61ua5Q05Cyz-pLwVjpw@mail.gmail.com>
Hi Andy,
Forgot to reply to the sysfs suggestion.
On Mon, 2021-05-24 at 15:54 +0300, Andy Shevchenko wrote:
> On Mon, May 24, 2021 at 2:41 PM Sander Vanheule <sander@svanheule.net> wrote:
> > On Mon, 2021-05-24 at 10:53 +0300, Andy Shevchenko wrote:
> > > On Mon, May 24, 2021 at 4:11 AM Andrew Lunn <andrew@lunn.ch> wrote:
>
> > > > > - Introduce GPIO regmap quirks to set output direction first
> > > >
> > > > I thought you had determined it was possible to set output before
> > > > direction?
> > >
> > > Same thoughts when I saw an updated version of that patch. My
> > > anticipation was to not see it at all.
> >
> > The two devices I've been trying to test the behaviour on are:
> > * Netgear GS110TPP: has an RTL8231 with three LEDs, each driven via a pin
> > configured as (active-low) GPIO. The LEDs are easy for a quick visual
> > check.
> > * Zyxel GS1900-8: RTL8231 used for the front panel button, and an active-
> > low
> > GPIO used to hard reset the main SoC (an RTL8380). I've modified this
> > board
> > to change some of the strapping pin values, but testing with the jumpers
> > and
> > pull-up/down resistors is a bit more tedious.
> >
> > On the Netgear, I tested the following with and without the quirk:
> >
> > # Set as OUT-LOW twice, to avoid the quirk. Always turns the LED on
> > gpioset 1 32=0; gpioset 1 32=0
> > # Get value to change to input, turns the LED off (high impedance)
> > # Will return 1 due to (weak) internal pull-up
> > gpioget 1 32
> > # Set as OUT-HIGH, should result in LED off
> > # When the quirk is disabled, the LED turns on (i.e. old OUT-LOW value)
> > # When the quirk is enabled, the LED remains off (i.e. correct OUT-HIGH
> > value)
> > gpioset 1 32=1
> >
> > Now, what's confusing (to me) is that the inverse doesn't depend on the
> > quirk:
> >
> > # Set as OUT-HIGH twice
> > gpioset 1 32=1; gpioset 1 32=1
> > # Change to high-Z
> > gpioget 1 32
> > # Set to OUT-LOW, always results in LED on, with or without quirk
> > gpioset 1 32=0
> >
> > Any idea why this would be (or appear) broken on the former case, but not on
> > the
> > latter?
>
> GPIO tools for the shell are context-less. Can you reproduce this with
> the legacy sysfs interface?
Using the sysfs interface produced the same behaviour for both test cases.
E.g. case 1:
# Set to output low
echo out > direction; echo 0 > value
# Change to input (with weak pull-up)
echo in > direction
# Try to set to output high
# Fails to go high if the pin value is set before the direction
echo high > direction
Best,
Sander
next prev parent reply other threads:[~2021-05-24 16:09 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 12:25 [PATCH 0/5] RTL8231 GPIO expander support Sander Vanheule
2021-05-11 12:25 ` [PATCH 1/5] dt-bindings: leds: Binding for RTL8231 scan matrix Sander Vanheule
2021-05-17 22:31 ` Rob Herring
2021-05-19 16:39 ` Sander Vanheule
2021-05-11 12:25 ` [PATCH 2/5] dt-bindings: mfd: Binding for RTL8231 Sander Vanheule
2021-05-17 22:38 ` Rob Herring
2021-05-19 16:53 ` Sander Vanheule
2021-05-11 12:25 ` [PATCH 3/5] mfd: Add RTL8231 core device Sander Vanheule
2021-05-12 12:29 ` kernel test robot
2021-05-12 13:13 ` kernel test robot
2021-05-19 14:58 ` Lee Jones
2021-05-19 15:11 ` Sander Vanheule
2021-05-11 12:25 ` [PATCH 4/5] pinctrl: Add RTL8231 pin control and GPIO support Sander Vanheule
2021-05-11 12:25 ` [PATCH 5/5] leds: Add support for RTL8231 LED scan matrix Sander Vanheule
[not found] ` <CAHp75VffoKyyPJbdtKMLx575c9LT0S8+EHOk7Mw36j=aTL6Q4Q@mail.gmail.com>
2021-05-16 21:40 ` [PATCH 0/5] RTL8231 GPIO expander support Sander Vanheule
2021-05-17 8:13 ` Andy Shevchenko
2021-05-17 8:50 ` Sander Vanheule
2021-05-17 19:32 ` Sander Vanheule
2021-05-17 19:28 ` [PATCH v2 0/7] " Sander Vanheule
2021-05-17 19:28 ` [PATCH v2 1/7] regmap: Add MDIO bus support Sander Vanheule
2021-05-19 16:12 ` Mark Brown
2021-05-17 19:28 ` [PATCH v2 2/7] gpio: regmap: Add configurable dir/value order Sander Vanheule
2021-05-17 21:06 ` Andy Shevchenko
2021-05-18 1:40 ` Andrew Lunn
2021-05-18 11:39 ` Sander Vanheule
2021-05-23 22:21 ` Sander Vanheule
2021-05-18 8:39 ` Michael Walle
2021-05-18 10:39 ` Andy Shevchenko
2021-05-23 21:19 ` Sander Vanheule
2021-05-17 19:28 ` [PATCH v2 3/7] dt-bindings: leds: Binding for RTL8231 scan matrix Sander Vanheule
2021-05-17 19:28 ` [PATCH v2 4/7] dt-bindings: mfd: Binding for RTL8231 Sander Vanheule
2021-05-18 22:02 ` Linus Walleij
2021-05-17 19:28 ` [PATCH v2 5/7] mfd: Add RTL8231 core device Sander Vanheule
2021-05-17 21:18 ` Andy Shevchenko
2021-05-23 21:28 ` Sander Vanheule
2021-05-24 7:49 ` Andy Shevchenko
2021-05-24 7:50 ` Sander Vanheule
2021-05-24 7:55 ` Andy Shevchenko
2021-05-24 8:04 ` Sander Vanheule
2021-05-17 19:28 ` [PATCH v2 6/7] pinctrl: Add RTL8231 pin control and GPIO support Sander Vanheule
2021-05-17 21:42 ` Andy Shevchenko
2021-05-17 21:46 ` Andy Shevchenko
2021-05-23 21:42 ` Sander Vanheule
2021-05-17 19:28 ` [PATCH v2 7/7] leds: Add support for RTL8231 LED scan matrix Sander Vanheule
2021-05-17 22:00 ` Andy Shevchenko
2021-05-23 21:53 ` Sander Vanheule
2021-05-19 16:10 ` (subset) [PATCH v2 0/7] RTL8231 GPIO expander support Mark Brown
2021-05-23 22:33 ` [PATCH v3 0/6] " Sander Vanheule
2021-05-23 22:33 ` [PATCH v3 1/6] gpio: regmap: Add quirk for output data register Sander Vanheule
2021-05-28 6:40 ` Michael Walle
2021-06-03 10:03 ` Sander Vanheule
2021-05-31 7:25 ` Bartosz Golaszewski
2021-05-23 22:34 ` [PATCH v3 2/6] dt-bindings: leds: Binding for RTL8231 scan matrix Sander Vanheule
2021-06-02 18:58 ` Rob Herring
2021-05-23 22:34 ` [PATCH v3 3/6] dt-bindings: mfd: Binding for RTL8231 Sander Vanheule
2021-05-27 23:31 ` Linus Walleij
2021-06-02 19:02 ` Rob Herring
2021-05-23 22:34 ` [PATCH v3 4/6] mfd: Add RTL8231 core device Sander Vanheule
2021-05-24 8:02 ` Andy Shevchenko
2021-05-24 8:23 ` Sander Vanheule
2021-05-24 10:18 ` Andy Shevchenko
2021-05-24 11:41 ` Sander Vanheule
2021-05-23 22:34 ` [PATCH v3 5/6] pinctrl: Add RTL8231 pin control and GPIO support Sander Vanheule
2021-05-28 6:29 ` Michael Walle
2021-05-28 6:42 ` Sander Vanheule
2021-05-28 6:43 ` Michael Walle
2021-05-23 22:34 ` [PATCH v3 6/6] leds: Add support for RTL8231 LED scan matrix Sander Vanheule
2021-05-24 10:24 ` Andy Shevchenko
2021-05-24 12:04 ` Sander Vanheule
2021-05-24 12:47 ` Andy Shevchenko
2021-05-24 15:30 ` Sander Vanheule
2021-05-24 1:10 ` [PATCH v3 0/6] RTL8231 GPIO expander support Andrew Lunn
2021-05-24 7:53 ` Andy Shevchenko
2021-05-24 11:41 ` Sander Vanheule
2021-05-24 12:54 ` Andy Shevchenko
2021-05-24 15:03 ` Sander Vanheule
2021-05-24 16:30 ` Andy Shevchenko
2021-05-25 17:11 ` Andy Shevchenko
2021-05-25 18:00 ` Sander Vanheule
2021-05-26 21:02 ` Sander Vanheule
2021-05-27 10:38 ` Andy Shevchenko
2021-05-27 10:41 ` Hans de Goede
2021-05-24 15:20 ` Sander Vanheule [this message]
2021-05-28 6:37 ` Michael Walle
2021-05-30 16:19 ` Sander Vanheule
2021-05-30 16:51 ` Hans de Goede
2021-05-30 18:16 ` Andy Shevchenko
2021-05-30 21:22 ` Michael Walle
2021-05-31 8:36 ` Sander Vanheule
2021-05-31 10:02 ` Michael Walle
[not found] ` <CAHp75VfOrUBRQH1vrXEwHN4ZPojQfQju-_wp_3djZeozEaatug@mail.gmail.com>
2021-05-31 15:33 ` [PATCH 0/5] " Sander Vanheule
2021-05-31 15:48 ` Andy Shevchenko
2021-06-01 11:49 ` Michael Walle
2021-06-01 15:24 ` Andy Shevchenko
2021-06-02 20:20 ` Sander Vanheule
2021-06-01 9:59 ` [PATCH v3 0/6] " Linus Walleij
2021-06-01 10:18 ` Michael Walle
2021-06-01 10:51 ` Linus Walleij
2021-06-01 11:41 ` Michael Walle
2021-06-01 11:48 ` Linus Walleij
2021-06-03 10:00 ` [PATCH v4 0/5] " Sander Vanheule
2021-06-03 10:00 ` [PATCH v4 1/5] dt-bindings: leds: Binding for RTL8231 scan matrix Sander Vanheule
2021-06-03 10:00 ` [PATCH v4 2/5] dt-bindings: mfd: Binding for RTL8231 Sander Vanheule
2021-06-03 10:00 ` [PATCH v4 3/5] mfd: Add RTL8231 core device Sander Vanheule
2021-06-03 10:58 ` Andy Shevchenko
2021-06-03 11:28 ` Sander Vanheule
2021-06-03 14:03 ` Andrew Lunn
2021-06-03 15:20 ` Sander Vanheule
2021-06-05 11:07 ` Sander Vanheule
2021-06-03 10:00 ` [PATCH v4 4/5] pinctrl: Add RTL8231 pin control and GPIO support Sander Vanheule
2021-06-03 10:18 ` Andy Shevchenko
2021-06-04 22:10 ` Linus Walleij
2021-06-03 10:00 ` [PATCH v4 5/5] leds: Add support for RTL8231 LED scan matrix Sander Vanheule
2021-06-03 11:01 ` Andy Shevchenko
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