linux-kernel - Re: [PATCH 3/4] iio: pressure: Add timestamp and scan

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Message-ID: <ZeW048EyOAze7oZR@smile.fi.intel.com>
Date: Mon, 4 Mar 2024 13:47:47 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Vasileios Amoiridis <vassilisamir@...il.com>
Cc: jic23@...nel.org, lars@...afoo.de, ang.iglesiasg@...il.com,
	mazziesaccount@...il.com, ak@...klinger.de,
	petre.rodan@...dimension.ro, phil@...pberrypi.com, 579lpy@...il.com,
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] iio: pressure: Add timestamp and scan_masks for
 BMP280 driver

On Sun, Mar 03, 2024 at 05:52:59PM +0100, Vasileios Amoiridis wrote:
> The scan mask for the BME280 device which contains humidity
> measurement needs to become different in order for the timestamp
> to be able to work. Scan masks are added for different combinations
> of measurements. The temperature measurement is needed for either
> pressure or humidity measurements.

..

> +enum bmp280_scan {
> +	BMP280_TEMP,
> +	BMP280_PRESS,
> +	BME280_HUMID,
> +};

Hmm... Why do we need to actually copy the IIO ones? Can't we use IIO ones
directly (or in some way)?

..

> +static const unsigned long bmp280_avail_scan_masks[] = {
> +	BIT(BMP280_TEMP),
> +	BIT(BMP280_PRESS) | BIT(BMP280_TEMP),
> +	0,

No comma for the terminator line.

> +};

> +static const unsigned long bme280_avail_scan_masks[] = {
> +	BIT(BMP280_TEMP),
> +	BIT(BMP280_PRESS) | BIT(BMP280_TEMP),
> +	BIT(BME280_HUMID) | BIT(BMP280_TEMP),
> +	BIT(BME280_HUMID) | BIT(BMP280_PRESS) | BIT(BMP280_TEMP),
> +	0,

Ditto.

> +};

..

>  	const struct iio_chan_spec *channels;
>  	int num_channels;
> +	const unsigned long *avail_scan_masks;
>  	unsigned int start_up_time;

Please, run `pahole` every time you are changing data structure layout.
Here you efficiently wasted 8 bytes of memory AFAICS.

-- 
With Best Regards,
Andy Shevchenko