From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Sander Vanheule <sander@svanheule.net>
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: Tue, 25 May 2021 20:11:50 +0300 [thread overview]
Message-ID: <CAHp75VfCBtcQX4rvmQnRMquM0k7ZBqOgZN15Z7TFNSO60SB9TA@mail.gmail.com> (raw)
In-Reply-To: <CAHp75VfzEwVGR7ttdcKzirPDN8oUFw1uTDXPFE=P=9+S3CAFYQ@mail.gmail.com>
On Mon, May 24, 2021 at 7:30 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Mon, May 24, 2021 at 6:03 PM Sander Vanheule <sander@svanheule.net> wrote:
> > On Mon, 2021-05-24 at 15:54 +0300, Andy Shevchenko wrote:
...
> > Sadly, I don't. Most of the info we have comes from code archives of switch
> > vendors (Zyxel, Cisco etc). Boards need to be reverse engineered, and the few
> > leaked datasheets that can be found on the internet aren't exactly thick in
> > information.
> >
> > The RTL8231 datasheet is actually quite useful, but makes no mention of the
> > output value isse. Since this isn't an official resource, I don't think it would
> > be appropriate to link it via a Datasheet: tag.
> > https://github.com/libc0607/Realtek_switch_hacking/blob/files/RTL8231_Datasheet_
> > 1.2.pdf
> >
> > Looking at the datasheet again, I came up with a... terrible hack to work around
> > the output value issue.
> >
> > The chip also has GPIO_INVERT registers that I hadn't used until now, because
> > the logical inversion is handled in the kernel. However, these inversion
> > registers only apply to the output values. So, I could implement glitch-free
> > output behaviour in the following way:
> > * After chip reset, and before enabling the output driver (MFD initialisation):
> > - Mux all pins as GPIO
> > - Change all pins to outputs,
>
> No. no, no. This is much worse than the glitches. You never know what
> the hardware is connected there and it's potential breakage (on hw
> level) possible.
>
> > so the data registers (0x1c-0x1e) become writable
> > - Write value 0 to all pins
> > - Change all pins to GPI to change them into high-Z
> > * In the pinctrl/gpio driver:
> > - Use data registers as input-only
> > - Use inversion register to determine output value (can be written any time)
> >
> > The above gives glitch-free outputs, but the values that are read back (when
> > configured as output), come from the data registers. They should now be coming
> > from the inversion (reg_set_base) registers, but the code prefers to use the
> > data registers (reg_dat_base).
>
> Lemme read the datasheet and see if I find any clue for the hw behaviour.
Thank you for your patience!
Have you explored the possibility of using En_Sync_GPIO?
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2021-05-25 17:12 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 [this message]
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
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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