linux-kernel - Re: [PATCH v10 08/13] regulator: bd718x7: Split driver to common and bd718x7 specific parts

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Message-ID: <4bd035fb2c78e96f18006f06c5d8d9d2f1a1b70d.camel@fi.rohmeurope.com>
Date:   Fri, 17 Jan 2020 10:43:52 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     "lee.jones@...aro.org" <lee.jones@...aro.org>
CC:     "linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
        "dmurphy@...com" <dmurphy@...com>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mturquette@...libre.com" <mturquette@...libre.com>,
        "mazziesaccount@...il.com" <mazziesaccount@...il.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "jacek.anaszewski@...il.com" <jacek.anaszewski@...il.com>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "bgolaszewski@...libre.com" <bgolaszewski@...libre.com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "sboyd@...nel.org" <sboyd@...nel.org>,
        "pavel@....cz" <pavel@....cz>,
        "broonie@...nel.org" <broonie@...nel.org>
Subject: Re: [PATCH v10 08/13] regulator: bd718x7: Split driver to common
 and bd718x7 specific parts

Hello Lee,

On Fri, 2020-01-17 at 10:28 +0000, Lee Jones wrote:
> On Fri, 17 Jan 2020, Matti Vaittinen wrote:
> 
> > Few ROHM PMICs allow setting the voltage states for different
> > system states
> > like RUN, IDLE, SUSPEND and LPSR. States are then changed via SoC
> > specific
> > mechanisms. bd718x7 driver implemented device-tree parsing
> > functions for
> > these state specific voltages. The parsing functions can be re-used 
> > by
> > other ROHM chip drivers like bd71828. Split the generic functions
> > from
> > bd718x7-regulator.c to rohm-regulator.c and export them for other
> > modules
> > to use.
> > 
> > Signed-off-by: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
> > Acked-by: Mark Brown <broonie@...nel.org>
> > ---
> > no changes since v9
> > 
> >  drivers/regulator/Kconfig             |   4 +
> >  drivers/regulator/Makefile            |   1 +
> >  drivers/regulator/bd718x7-regulator.c | 183 ++++++++------------
> > ------
> >  drivers/regulator/rohm-regulator.c    |  95 +++++++++++++
> >  include/linux/mfd/rohm-generic.h      |  66 ++++++++++
> >  5 files changed, 221 insertions(+), 128 deletions(-)
> >  create mode 100644 drivers/regulator/rohm-regulator.c
> 
> [...]
> 
> > diff --git a/include/linux/mfd/rohm-generic.h
> > b/include/linux/mfd/rohm-generic.h
> > index ff3dd7578fd3..6cc5a0819959 100644
> > --- a/include/linux/mfd/rohm-generic.h
> > +++ b/include/linux/mfd/rohm-generic.h
> > @@ -4,6 +4,9 @@
> >  #ifndef __LINUX_MFD_ROHM_H__
> >  #define __LINUX_MFD_ROHM_H__
> >  
> > +#include <linux/regmap.h>
> > +#include <linux/regulator/driver.h>
> > +
> >  enum rohm_chip_type {
> >  	ROHM_CHIP_TYPE_BD71837 = 0,
> >  	ROHM_CHIP_TYPE_BD71847,
> > @@ -17,4 +20,67 @@ struct rohm_regmap_dev {
> >  	struct regmap *regmap;
> >  };
> >  
> > +enum {
> > +	ROHM_DVS_LEVEL_UNKNOWN,
> > +	ROHM_DVS_LEVEL_RUN,
> > +	ROHM_DVS_LEVEL_IDLE,
> > +	ROHM_DVS_LEVEL_SUSPEND,
> > +	ROHM_DVS_LEVEL_LPSR,
> > +#define ROHM_DVS_LEVEL_MAX ROHM_DVS_LEVEL_LPSR
> 
> Haven't seen this before.  Is it legit?
> 

I don't know why it wouldn't be :) I kind of grew used to that when I
still did some networking stuff.

It doesn't really matter in this case but for example the netlink
headers do:

enum {
   foo,
#define foo foo
   bar,
#define bar bar
...
};

https://elixir.bootlin.com/linux/v5.5-rc6/source/include/uapi/linux/rtnetlink.h

What is the good here is that this allows one to nicely exclude
unsupported stuff using preprocessor:

#include <header_with_or_without_foo_dependng_on_version.h>

#ifdef foo
use_foo(foo);
#endif

What about:
> 
>      ROHM_DVS_LEVEL_MAX = ROHM_DVS_LEVEL_LPSR

Anyways, I don't see why define wouldn't be Ok here - but sure it can
be changed if you insist ;) Just let me know if you can accept the
define or not :)


>