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From: Michael Walle <michael@walle.cc>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Sander Vanheule <sander@svanheule.net>,
	Hans de Goede <hdegoede@redhat.com>, 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>,
	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 0/5] RTL8231 GPIO expander support
Date: Tue, 01 Jun 2021 13:49:38 +0200	[thread overview]
Message-ID: <8df77f619730b9e7b5cdd7ddefb60a03@walle.cc> (raw)
In-Reply-To: <CAHp75Vcb95HiYxvEzYr0QXcQmA_A+2M9M0uv6PAhPHtgTges8g@mail.gmail.com>

Am 2021-05-31 17:48, schrieb Andy Shevchenko:
> On Mon, May 31, 2021 at 6:33 PM Sander Vanheule <sander@svanheule.net> 
> wrote:
>> On Mon, 2021-05-31 at 14:16 +0300, Andy Shevchenko wrote:
>> > On Monday, May 31, 2021, Michael Walle <michael@walle.cc> wrote:
>> > > Am 2021-05-31 10:36, schrieb Sander Vanheule:
> 
>> Am I missing something here? It seems to me like the regmap interface 
>> can't
>> really accommodate what's required, unless maybe the rtl8231 regmap 
>> users
>> perform some manual locking. This all seems terribly complicated 
>> compared to
>> using an internal output-value cache inside regmap-gpio.
> 
> Have you had a chance to look into the PCA953x driver?
> Sounds to me that you are missing the APIs that regmap provides.

What would that be? The register cache? We need to cache the
value somehow, because (still assuming it is write only) we cannot
read it back. Thus the read of the RMW, would need get the
value from the cache. Thus the user of gpio-regmap would need
to make sure, to (a) use a cache for the regmap supplied to
gpio-regmap and (b) populate its initial values correctly. Is
that what you are suggesting? And hopefully, no other user
of the regmap will call regcache_mark_dirty() or something
like that.

I had a quick look at the PCA953x driver but it all its
registers are readable according to the comment on the top
of the file.

-michael

  reply	other threads:[~2021-06-01 11:49 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
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 [this message]
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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