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From: Linus Walleij <linus.walleij@linaro.org>
To: Michael Walle <michael@walle.cc>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Sander Vanheule <sander@svanheule.net>,
	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>,
	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, 1 Jun 2021 13:48:43 +0200	[thread overview]
Message-ID: <CACRpkdYSMjDaRY2chbFyBTJ4jeAjPtXX3+VW7MHu-wH2QoAfPA@mail.gmail.com> (raw)
In-Reply-To: <401805ef27bb273d7aca4f3377b53b07@walle.cc>

On Tue, Jun 1, 2021 at 1:41 PM Michael Walle <michael@walle.cc> wrote:
> Am 2021-06-01 12:51, schrieb Linus Walleij:
> > On Tue, Jun 1, 2021 at 12:18 PM Michael Walle <michael@walle.cc> wrote:
> >> Am 2021-06-01 11:59, schrieb Linus Walleij:
> >
> >> > Just regarding all registers/memory cells in a register page
> >> > as default volatile (which is what we do a lot of the time)
> >> > has its upsides: bugs like this doesn't happen.
> >>
> >> I don't think this is the bug here. If it is really a write-only
> >> register
> >> the problem is the read in RMW. Because reading the register will
> >> return
> >> the input value instead of the (previously written) output value.
> >
> > True that. Write and read semantics differ on the register.
> >
> > Volatile is used for this and some other things,
> > like for example interrupts being cleared when a register
> > is read so it is strictly read-once.
>
> Isn't that what precious is for?

I never figured that one out. But I assume you are right.

Proper regmap semantics documentation is forthcoming! ;)

Yours,
Linus Walleij

  reply	other threads:[~2021-06-01 11:48 UTC|newest]

Thread overview: 124+ 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 12:29     ` kernel test robot
2021-05-12 13:13   ` kernel test robot
2021-05-12 13:13     ` kernel test robot
2021-05-19 14:58     ` Lee Jones
2021-05-19 14:58       ` Lee Jones
2021-05-19 15:11       ` Sander Vanheule
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
     [not found]     ` <CAHp75VfCCFd9SQwqv-JhdHMudYWdaa1tcVp4ZNescioWTaoXFQ@mail.gmail.com>
2021-05-24 11:32       ` Andy Shevchenko
2021-05-24 11:39         ` 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
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 [this message]
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
2021-06-03 15:58     ` kernel test robot
2021-06-03 15:58       ` kernel test robot
2021-06-04  7:00       ` Sander Vanheule
2021-06-04  7:00         ` Sander Vanheule
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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