linux-kernel - Re: [PATCH v3 1/7] iio: pressure: bmp280: Use bulk read for humidity calibration data

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Message-ID: <ZsjZOkglW1lGDNr8@smile.fi.intel.com>
Date: Fri, 23 Aug 2024 21:47:22 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Vasileios Amoiridis <vassilisamir@...il.com>
Cc: jic23@...nel.org, lars@...afoo.de, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, ang.iglesiasg@...il.com,
	linus.walleij@...aro.org, biju.das.jz@...renesas.com,
	javier.carrasco.cruz@...il.com, semen.protsenko@...aro.org,
	579lpy@...il.com, ak@...klinger.de, linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/7] iio: pressure: bmp280: Use bulk read for humidity
 calibration data

On Fri, Aug 23, 2024 at 08:17:08PM +0200, Vasileios Amoiridis wrote:
> Convert individual reads to a bulk read for the humidity calibration data.

...

> +	calib->H2 = get_unaligned_le16(&data->bme280_humid_cal_buf[H2]);
> +	calib->H3 = data->bme280_humid_cal_buf[H3];

> +	h4_upper = FIELD_GET(BME280_COMP_H4_GET_MASK_UP,
> +			get_unaligned_be16(&data->bme280_humid_cal_buf[H4]));
> +	h4_upper = FIELD_PREP(BME280_COMP_H4_PREP_MASK_UP, h4_upper);

This is a bit confusing. I would add a tmp variable and have this as

	tmp = FIELD_GET(BME280_COMP_H4_GET_MASK_UP,
			get_unaligned_be16(&data->bme280_humid_cal_buf[H4]));
	h4_upper = FIELD_PREP(BME280_COMP_H4_PREP_MASK_UP, tmp);

Also note indentation issues.

> +	h4_lower = FIELD_GET(BME280_COMP_H4_MASK_LOW,
> +			get_unaligned_be16(&data->bme280_humid_cal_buf[H4]));
> +	calib->H4 = sign_extend32(h4_upper | h4_lower, 11);
> +	calib->H5 = sign_extend32(FIELD_GET(BME280_COMP_H5_MASK,
> +			get_unaligned_le16(&data->bme280_humid_cal_buf[H5])), 11);
> +	calib->H6 = data->bme280_humid_cal_buf[H6];

...

>  		/* Calibration data buffers */
>  		__le16 bmp280_cal_buf[BMP280_CONTIGUOUS_CALIB_REGS / 2];
>  		__be16 bmp180_cal_buf[BMP180_REG_CALIB_COUNT / 2];

Side note: I would see rather sizeof(__Xe16) than 2:s in the above definitions.

> +		u8 bme280_humid_cal_buf[BME280_CONTIGUOUS_CALIB_REGS];

-- 
With Best Regards,
Andy Shevchenko