From: Lee Jones <lee.jones@linaro.org>
To: Michael Walle <michael@walle.cc>
Cc: "Andy Shevchenko" <andy.shevchenko@gmail.com>,
"Ranjani Sridharan" <ranjani.sridharan@linux.intel.com>,
david.m.ertman@intel.com, shiraz.saleem@intel.com,
"Rob Herring" <robh+dt@kernel.org>,
"Mark Brown" <broonie@kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
devicetree <devicetree@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-hwmon@vger.kernel.org, linux-pwm@vger.kernel.org,
linux-watchdog@vger.kernel.org,
"linux-arm Mailing List" <linux-arm-kernel@lists.infradead.org>,
"Linus Walleij" <linus.walleij@linaro.org>,
"Bartosz Golaszewski" <bgolaszewski@baylibre.com>,
"Jean Delvare" <jdelvare@suse.com>,
"Guenter Roeck" <linux@roeck-us.net>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Wim Van Sebroeck" <wim@linux-watchdog.org>,
"Shawn Guo" <shawnguo@kernel.org>, "Li Yang" <leoyang.li@nxp.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Jason Cooper" <jason@lakedaemon.net>,
"Marc Zyngier" <maz@kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>
Subject: Re: [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller
Date: Wed, 10 Jun 2020 08:56:15 +0100 [thread overview]
Message-ID: <20200610075615.GT4106@dell> (raw)
In-Reply-To: <f7b2b690750edd022000ab56d2f58154@walle.cc>
On Wed, 10 Jun 2020, Michael Walle wrote:
> Am 2020-06-10 09:19, schrieb Lee Jones:
> > On Wed, 10 Jun 2020, Michael Walle wrote:
> > > Am 2020-06-09 21:45, schrieb Lee Jones:
> > > > On Tue, 09 Jun 2020, Michael Walle wrote:
> > > > > > We do not need a 'simple-regmap' solution for your use-case.
> > > > > >
> > > > > > Since your device's registers are segregated, just split up the
> > > > > > register map and allocate each sub-device with it's own slice.
> > > > >
> > > > > I don't get it, could you make a device tree example for my
> > > > > use-case? (see also above)
> > > >
> > > > &i2cbus {
> > > > mfd-device@10 {
> > > > compatible = "simple-mfd";
> > > > reg = <10>;
> > > >
> > > > sub-device@10 {
> > > > compatible = "vendor,sub-device";
> > > > reg = <10>;
> > > > };
> > > > };
> > > >
> > > > The Regmap config would be present in each of the child devices.
> > > >
> > > > Each child device would call devm_regmap_init_i2c() in .probe().
> > >
> > > Ah, I see. If I'm not wrong, this still means to create an i2c
> > > device driver with the name "simple-mfd".
> >
> > Yes, it does.
> >
> > > Besides that, I don't like this, because:
> > > - Rob already expressed its concerns with "simple-mfd" and so on.
> >
> > Where did this take place? I'd like to read up on this.
>
> In this thread:
> https://lore.kernel.org/linux-devicetree/20200604211039.12689-1-michael@walle.cc/T/#m16fdba5962069e7cd4aa817582ee358c9fe2ecbf
>
> >
> > > - you need to duplicate the config in each sub device
> >
> > You can have a share a single config.
> >
> > > - which also means you are restricting the sub devices to be
> > > i2c only (unless you implement and duplicate other regmap configs,
> > > too). For this driver, SPI and MMIO may be viable options.
> >
> > You could also have a shared implementation to choose between different
> > busses.
>
> Then what is the difference between to have this shared config in the
> parent driver only and use the functions which are already there, i.e.
> dev_get_regmap(parent). But see, below, I'll wait with what you're
> coming up.
The difference is the omission of an otherwise pointless/superfluous
driver. Actually, it's the difference between the omission of 10
pointless drivers!
> > > Thus, I'd rather implement a simple-mfd.c which implement a common
> > > I2C driver for now and populate its children using
> > > devm_of_platform_populate(). This could be extended to support other
> > > type of regmaps like SPI in the future.
> > >
> > > Also some MFD drivers could be moved to this, a likely candidate is
> > > the smsc-ece1099.c. Although I don't really understand its purpose,
> > > if don't have CONFIG_OF.
> > >
> > > Judging from the existing code, this simple-mfd.c wouldn't just be
> > > "a list of compatible" strings but also additional quirks and tweaks
> > > for particular devices in this list.
> >
> > Hold off on the simple-mfd.c idea, as I'm not taken by it yet and
> > wouldn't want you to waste your time. I have another idea which would
> > help. Give me a few days to put something together.
>
> Sure. I'm just glad there is now a discussion about this issue.
It's very much in my mind.
I've been meaning to do something about it for quite some time.
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
next prev parent reply other threads:[~2020-06-10 7:56 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-04 21:10 [PATCH v4 00/11] Add support for Kontron sl28cpld Michael Walle
2020-06-04 21:10 ` [PATCH v4 01/11] dt-bindings: mfd: Add bindings for sl28cpld Michael Walle
2020-06-09 16:28 ` Rob Herring
2020-06-04 21:10 ` [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller Michael Walle
2020-06-05 6:57 ` Lee Jones
2020-06-05 9:51 ` Michael Walle
2020-06-05 10:50 ` Mark Brown
2020-06-05 20:07 ` Michael Walle
2020-06-06 11:46 ` Mark Brown
2020-06-06 12:45 ` Michael Walle
2020-06-08 8:28 ` Lee Jones
2020-06-08 10:02 ` Andy Shevchenko
2020-06-08 15:41 ` Michael Walle
2020-06-08 18:56 ` Lee Jones
2020-06-08 21:09 ` Michael Walle
2020-06-09 6:47 ` Lee Jones
2020-06-09 14:38 ` Michael Walle
2020-06-09 14:42 ` Mark Brown
2020-06-09 15:01 ` Michael Walle
2020-06-09 17:15 ` Rob Herring
2020-06-09 17:29 ` Mark Brown
2020-06-09 18:41 ` Lee Jones
2020-06-09 15:19 ` Lee Jones
2020-06-09 15:30 ` Michael Walle
2020-06-09 19:45 ` Lee Jones
2020-06-10 7:10 ` Michael Walle
2020-06-10 7:19 ` Lee Jones
2020-06-10 7:49 ` Michael Walle
2020-06-10 7:56 ` Lee Jones [this message]
2020-06-10 9:27 ` Michael Walle
2020-06-10 18:30 ` Lee Jones
2020-06-10 17:16 ` Rob Herring
2020-06-10 18:02 ` Lee Jones
2020-06-08 18:20 ` Lee Jones
2020-06-09 16:54 ` Rob Herring
2020-06-09 18:52 ` Lee Jones
2020-06-05 8:01 ` Andy Shevchenko
2020-06-05 8:02 ` Andy Shevchenko
2020-06-05 10:09 ` Michael Walle
2020-06-05 10:48 ` Andy Shevchenko
2020-06-05 11:51 ` Michael Walle
2020-06-04 21:10 ` [PATCH v4 03/11] irqchip: add sl28cpld interrupt controller support Michael Walle
2020-06-05 1:26 ` kernel test robot
2020-06-05 8:07 ` Andy Shevchenko
2020-06-08 15:12 ` kernel test robot
2020-06-04 21:10 ` [PATCH v4 04/11] watchdog: add support for sl28cpld watchdog Michael Walle
2020-06-05 8:14 ` Andy Shevchenko
2020-06-05 10:24 ` Michael Walle
2020-06-05 10:50 ` Andy Shevchenko
2020-06-05 13:52 ` Guenter Roeck
2020-06-05 14:09 ` Andy Shevchenko
2020-06-05 15:05 ` Guenter Roeck
2020-06-05 16:04 ` Andy Shevchenko
2020-06-05 16:34 ` Guenter Roeck
2020-06-04 21:10 ` [PATCH v4 05/11] pwm: add support for sl28cpld PWM controller Michael Walle
2020-06-05 8:15 ` Andy Shevchenko
2020-06-05 8:49 ` Lee Jones
2020-06-05 9:33 ` Andy Shevchenko
2020-06-05 11:39 ` Michael Walle
2020-06-05 18:17 ` Michael Walle
2020-06-08 7:46 ` Lee Jones
2020-06-04 21:10 ` [PATCH v4 06/11] gpio: add support for the sl28cpld GPIO controller Michael Walle
2020-06-05 12:00 ` Andy Shevchenko
2020-06-05 12:42 ` Michael Walle
2020-06-05 13:15 ` Andy Shevchenko
2020-06-05 18:44 ` Michael Walle
2020-06-05 21:19 ` Andy Shevchenko
2020-06-04 21:10 ` [PATCH v4 07/11] hwmon: add support for the sl28cpld hardware monitoring controller Michael Walle
2020-06-05 12:06 ` Andy Shevchenko
2020-06-04 21:10 ` [PATCH v4 08/11] arm64: dts: freescale: sl28: enable sl28cpld Michael Walle
2020-06-04 21:10 ` [PATCH v4 09/11] arm64: dts: freescale: sl28: map GPIOs to input events Michael Walle
2020-06-04 21:10 ` [PATCH v4 10/11] arm64: dts: freescale: sl28: enable LED support Michael Walle
2020-06-04 21:10 ` [PATCH v4 11/11] arm64: dts: freescale: sl28: enable fan support Michael Walle
2020-06-05 6:13 ` [PATCH v4 00/11] Add support for Kontron sl28cpld Lee Jones
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