linux-kernel - Re: [PATCH v6 09/10] power: supply: Support ROHM bd99954 charger

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Message-ID: <d533c18dcd7b4d4ca453661b3f9495a840b3313b.camel@fi.rohmeurope.com>
Date:   Wed, 25 Mar 2020 13:00:21 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>
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Subject: Re: [PATCH v6 09/10] power: supply: Support ROHM bd99954 charger

Well, Good morning Andy :)

On Wed, 2020-03-25 at 14:09 +0200, andriy.shevchenko@...ux.intel.com
wrote:
> On Wed, Mar 25, 2020 at 11:36:46AM +0000, Vaittinen, Matti wrote:
> > On Tue, 2020-03-24 at 12:35 +0200, Andy Shevchenko wrote:
> > > On Tue, Mar 24, 2020 at 11:50:24AM +0200, Andy Shevchenko wrote:
> > > > On Tue, Mar 24, 2020 at 10:32:19AM +0200, Matti Vaittinen
> > > > wrote:
> > > > > +#include <linux/acpi.h>
> > > > > +#include <linux/of.h>
> > > > 
> > > > I didn't find any evidence of use of those two, otherwise,
> > > > missed
> > > > property.h
> > > > and perhaps mod_devicetable.h.
> 
> ...
> 
> > > > > +MODULE_DEVICE_TABLE(of, bd9995x_of_match);
> > > > > +MODULE_DEVICE_TABLE(acpi, bd9995x_acpi_match);
> > > 
> > > I have to add since you are using those macros without ifdeffery,
> > > you
> > > should
> > > get warning in !ACPI and/or !OF cases.
> > > 
> > > So, drop those of_match_ptr() / ACPI_PTR() and thus above
> > > headers.
> > 
> > Sorry but I don't follow :/ I did drop whole ACPI table as the
> > battery
> > information is not fetched from ACPI anyways.
> 
> Okay, let's forget then about ACPI bits.
> 
> > But I don't know what you
> > mean by dropping the of_match_ptr?
> 
> Literally do not use this macro. Otherwise you make a dependency to
> OF which
> should be then in the Kconfig like
> 
> 	depend on OF || COMPILE_TEST
> 

Hmm... Why is that? In of.h we have #ifndef CONFIG_OF section which
defines:

#define of_match_ptr(_ptr)	NULL

So, this macro is well defined even if !CONFIG_OF, right?


> but in this case you will get compiler warning without ugly ifdeffery
> around
> OF ID table (as you pointed below you didn't test that scenario).
> 
> > I for sure need the of_device_id as
> > in many cases both the device matching and module matching are done
> > based on  of_match_table and of_device_id.
> > 
> > I admit I didn't try compiling the !OF config. Are you suggesting I
> > should put the of_device_id array and populating the of_match_table
> > in
> > #ifdef CONFIG_OF? Or maybe you suggest that I will put of_device_id
> > array in #ifdef CONFIG_OF and use of_match_ptr() when populating
> > the
> > of_match_table pointer? I guess that would make sense. I'll do that
> > -
> > can you please explain if this was not what you meant.
> 
> One of us needs a morning covfefe, I think :-)

So in !CONFIG_OF case we will have
.of_match_table = of_match_ptr(bd9995x_of_match),
preprocessed to form
.of_match_table = NULL,

right? So with this macro we can omit introduction of bd9995x_of_match
when !CONFIG_OF - meaning we only build #ifdeffery arounf the match
table and not around this assignment.

So I'll just do 

#ifdef CONFIG_OF   
static const struct of_device_id bd9995x_of_match[] = {
        { .compatible = "rohm,bd99954", },
        { }
};          
MODULE_DEVICE_TABLE(of, bd9995x_of_match);
#endif

and let the
#define of_match_ptr(_ptr)	NULL
fix assignment
.of_match_table = of_match_ptr(bd9995x_of_match),

when !CONFIG_OF.

Br,
	Matti