linux-kernel - Re: [PATCH V1 1/1] iio: accel: sca3300: Extend the trigger buffer from 16 to 32 bytes

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Date:   Fri, 1 Jul 2022 17:46:02 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
Cc:     lars@...afoo.de, tomas.melin@...sala.com, nuno.sa@...log.com,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        bsp-development.geo@...ca-geosystems.com
Subject: Re: [PATCH V1 1/1] iio: accel: sca3300: Extend the trigger buffer
 from 16 to 32 bytes

On Fri,  1 Jul 2022 02:30:30 +0000
LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn> wrote:

> After added inclination angle channels, the trigger buffer size is
> insufficient. Extend the buffer size from 16 to 32 bytes, and change
> the trigger buffer from the struct to a u8 array to adapt the sensor
> with/without inclination angles output.
> New trigger buffer data:
>   - SCA3300: 3 accel channels, temp, and timestamp.
>   - SCL3300: 3 accel channels, temp, 3 incli channels, and timestamp.
> Readjustment the scan index to make it consistent with the buffer data.
> 
> Signed-off-by: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>

Hi.

Looks good. A trivial suggestion inline to make the code a little more
'self documenting'.  It's a minor change so if you are happy with
the suggestion I can tweak that whilst applying.

Thanks,

Jonathan

> ---
>  drivers/iio/accel/sca3300.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/iio/accel/sca3300.c b/drivers/iio/accel/sca3300.c
> index 3c4827bfef53..820dfb635bf1 100644
> --- a/drivers/iio/accel/sca3300.c
> +++ b/drivers/iio/accel/sca3300.c
> @@ -47,12 +47,20 @@
>  #define SCL3300_REG_ANG_CTRL 0x0C
>  #define SCL3300_ANG_ENABLE   0x1F
>  
> +/*
> + * Buffer size max case:
> + * Three accel channels, two bytes per channel.
> + * Temperature channel, two bytes.
> + * Three incli channels, two bytes per channel.
> + * Timestamp channel, eight bytes.
> + */
> +#define SCA3300_MAX_BUFFER_SIZE (ALIGN(2 * 7, sizeof(s64)) + sizeof(s64))

Instead of the 2 use sizeof(s16)
 Also now you don't have timestamp in your enum sca3000_scan_indexes
you could add a 'tail' element to the enum such as SCA3000_SCAN_MAX then
use that instead of the 7 here.  Hopefully that would make
this more self documenting.

> +
>  enum sca3300_scan_indexes {
>  	SCA3300_ACC_X = 0,
>  	SCA3300_ACC_Y,
>  	SCA3300_ACC_Z,
>  	SCA3300_TEMP,
> -	SCA3300_TIMESTAMP,
>  	SCA3300_INCLI_X,
>  	SCA3300_INCLI_Y,
>  	SCA3300_INCLI_Z,
> @@ -140,10 +148,10 @@ static const struct iio_chan_spec scl3300_channels[] = {
>  	SCA3300_ACCEL_CHANNEL(SCA3300_ACC_Y, 0x2, Y),
>  	SCA3300_ACCEL_CHANNEL(SCA3300_ACC_Z, 0x3, Z),
>  	SCA3300_TEMP_CHANNEL(SCA3300_TEMP, 0x05),
> -	IIO_CHAN_SOFT_TIMESTAMP(4),
>  	SCA3300_INCLI_CHANNEL(SCA3300_INCLI_X, 0x09, X),
>  	SCA3300_INCLI_CHANNEL(SCA3300_INCLI_Y, 0x0A, Y),
>  	SCA3300_INCLI_CHANNEL(SCA3300_INCLI_Z, 0x0B, Z),
> +	IIO_CHAN_SOFT_TIMESTAMP(7),
>  };
>  
>  static const unsigned long sca3300_scan_masks[] = {
> @@ -184,7 +192,9 @@ struct sca3300_chip_info {
>   * @spi: SPI device structure
>   * @lock: Data buffer lock
>   * @chip: Sensor chip specific information
> - * @scan: Triggered buffer. Four channel 16-bit data + 64-bit timestamp
> + * @buffer: Triggered buffer:
> + *          -SCA3300: 4 channel 16-bit data + 64-bit timestamp
> + *          -SCL3300: 7 channel 16-bit data + 64-bit timestamp
>   * @txbuf: Transmit buffer
>   * @rxbuf: Receive buffer
>   */
> @@ -192,10 +202,7 @@ struct sca3300_data {
>  	struct spi_device *spi;
>  	struct mutex lock;
>  	const struct sca3300_chip_info *chip;
> -	struct {
> -		s16 channels[4];
> -		s64 ts __aligned(sizeof(s64));
> -	} scan;
> +	u8 buffer[SCA3300_MAX_BUFFER_SIZE] __aligned(sizeof(s64));
>  	u8 txbuf[4] __aligned(IIO_DMA_MINALIGN);
>  	u8 rxbuf[4];
>  };
> @@ -484,21 +491,21 @@ static irqreturn_t sca3300_trigger_handler(int irq, void *p)
>  	struct iio_dev *indio_dev = pf->indio_dev;
>  	struct sca3300_data *data = iio_priv(indio_dev);
>  	int bit, ret, val, i = 0;
> +	s16 *channels = (s16 *)data->buffer;
>  
>  	for_each_set_bit(bit, indio_dev->active_scan_mask,
>  			 indio_dev->masklength) {
> -		ret = sca3300_read_reg(data, sca3300_channels[bit].address,
> -				       &val);
> +		ret = sca3300_read_reg(data, indio_dev->channels[bit].address, &val);
>  		if (ret) {
>  			dev_err_ratelimited(&data->spi->dev,
>  				"failed to read register, error: %d\n", ret);
>  			/* handled, but bailing out due to errors */
>  			goto out;
>  		}
> -		data->scan.channels[i++] = val;
> +		channels[i++] = val;
>  	}
>  
> -	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
> +	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
>  					   iio_get_time_ns(indio_dev));
>  out:
>  	iio_trigger_notify_done(indio_dev->trig);