linux-kernel - RE: [PATCH v4 1/2] hwmon: tmp513: Add max_channels variable to struct tmp51x

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Message-ID: <OS0PR01MB592218CADC2F90290B0B727D86EFA@OS0PR01MB5922.jpnprd01.prod.outlook.com>
Date:   Wed, 6 Sep 2023 14:46:37 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Eric Tremblay <etremblay@...tech-controls.com>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Biju Das <biju.das.au@...il.com>
Subject: RE: [PATCH v4 1/2] hwmon: tmp513: Add max_channels variable to struct
 tmp51x_data

Hi Andy,

> Subject: Re: [PATCH v4 1/2] hwmon: tmp513: Add max_channels variable to
> struct tmp51x_data
> 
> On Tue, Sep 05, 2023 at 07:42:51PM +0100, Biju Das wrote:
> > The tmp512 chip has 3 channels whereas tmp513 has 4 channels. Avoid
> > using tmp51x_ids for this HW difference by replacing OF/ID table data
> > with maximum channels supported by the device.
> >
> > Replace id->max_channels variable from struct tmp51x_data and drop the
> > macros TMP51{2,3}_TEMP_CONFIG_DEFAULT as it can be derived from the
> > macro TMP51X_TEMP_CONFIG_DEFAULT and update the logic in
> > tmp51x_is_visible(),
> > tmp51x_read_properties() and tmp51x_init() using max_channels.
> >
> > While at it, drop enum tmp51x_ids as there is no user and remove
> > trailing comma in the terminator entry for OF table.
> 
> ...
> 
> > +#define TMP51X_TEMP_CONFIG_CONV_RATE	FIELD_PREP(GENMASK(9, 7), 0x7)
> > +#define TMP51X_TEMP_CONFIG_RC		BIT(10)
> > +#define TMP51X_TEMP_CHANNEL_MASK(n)	FIELD_PREP(GENMASK(14, 11), \
> > +						   GENMASK((n) - 1, 0))
> 
> Why do you need FIELD_PREP() for the pure constants here? Why can you
> simply define the constants in the proper place?

I think one can clearly understand the bit definitions and value from FIELD_PREP.

For eg:
GENMASK(14, 11)--> bits 11..14
GENMASK((n) - 1, 0)--> value 15 for 4 channels and 7 for 3 channels.

> 
> ...
> 
> > +#define TMP51X_TEMP_CONFIG_DEFAULT(n)	(TMP51X_TEMP_CONFIG_CONT | \
> > +			TMP51X_TEMP_CHANNEL_MASK(n) | \
> > +			TMP51X_TEMP_CONFIG_CONV_RATE | TMP51X_TEMP_CONFIG_RC)
> 
> This is better to read in a form of
> 
> #define TMP51X_TEMP_CONFIG_DEFAULT(n)					\
> 	(TMP51X_TEMP_CHANNEL_MASK(n) | TMP51X_TEMP_CONFIG_CONT |	\
> 	 TMP51X_TEMP_CONFIG_CONV_RATE | TMP51X_TEMP_CONFIG_RC)
> 

I just used the indentation suggested by Guenter.

Cheers,
Biju