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

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Message-ID: <ZPiPVZKXeDfLsU64@smile.fi.intel.com>
Date:   Wed, 6 Sep 2023 17:40:21 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Biju Das <biju.das.jz@...renesas.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-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

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?

...

> +#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)

-- 
With Best Regards,
Andy Shevchenko