Re: [PATCH v5 2/5] iio: pressure: bmp280: Fix alignment for DMA safety

From: Andy Shevchenko
Date: Mon Aug 08 2022 - 04:54:01 EST


On Sun, Aug 7, 2022 at 1:56 PM Angel Iglesias <ang.iglesiasg@xxxxxxxxx> wrote:
>
> Adds DMA-safe buffers to driver data struct to store raw data from sensors
>
> The multiple buffers used thorough the driver share the same memory
> allocated as part of the device data instance. The union containing
> the buffers is aligned to allow safe usage with DMA operations, such
> as regmap bulk read calls.

...

> #include <linux/completion.h>
> #include <linux/pm_runtime.h>
> #include <linux/random.h>

+ Blank line.

> +#include <asm/unaligned.h>

...

> + union {
> + /* sensor data buffer */
> + u8 data[3];
> + /* calibration data buffers */
> + __le16 bmp280_cal[BMP280_CONTIGUOUS_CALIB_REGS / 2];
> + __be16 bmp180_cal[BMP180_REG_CALIB_COUNT / 2];
> + } buf __aligned(IIO_DMA_MINALIGN);

Hmm... And which field in the struct defines which of the buffers is being used?
Also, do you need a non-anonymous union?

> };

...

> + /* parse temperature calibration data */

Be consistent! Check all your patches for the consistency (comments,
other code style, etc).

...

> + calib->H5 = sign_extend32(((get_unaligned_le16(data->buf.data) >> 4) & 0xfff), 11);

(It's not directly related to this change, but good to ask)
Are you going to change all those masks to use GENMASK()?

...

> + struct bmp180_calib *calib = &data->calib.bmp180;
> int ret;
> int i;
> - struct bmp180_calib *calib = &data->calib.bmp180;

Exactly my point given the previous patch, now you have a ping-pong
style of changes: the introduced line in the series is being touched
again in the very same series without any need.

...

> u8 oss = data->oversampling_press;
> + int ret;

Ditto.

--
With Best Regards,
Andy Shevchenko