linux-kernel - Re: [PATCH v3 7/7] iio: accel: Add support for Kionix/ROHM KX132-1211 accelerometer

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Date:   Fri, 5 May 2023 20:11:33 +0200
From:   Mehdi Djait <mehdi.djait.k@...il.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     mazziesaccount@...il.com, krzysztof.kozlowski+dt@...aro.org,
        andriy.shevchenko@...ux.intel.com, robh+dt@...nel.org,
        lars@...afoo.de, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v3 7/7] iio: accel: Add support for Kionix/ROHM
 KX132-1211 accelerometer

Hello Jonathan,

On Mon, May 01, 2023 at 03:56:45PM +0100, Jonathan Cameron wrote:
> On Tue, 25 Apr 2023 00:22:27 +0200
> Mehdi Djait <mehdi.djait.k@...il.com> wrote:
> 
> > Kionix KX132-1211 is a tri-axis 16-bit accelerometer that can support
> > ranges from ±2G to ±16G, digital output through I²C/SPI.
> > Add support for basic accelerometer features such as reading acceleration
> > via IIO using raw reads, triggered buffer (data-ready), or the WMI IRQ.
> > 
> > Datasheet: https://kionixfs.azureedge.net/en/document/KX132-1211-Technical-Reference-Manual-Rev-5.0.pdf
> > Signed-off-by: Mehdi Djait <mehdi.djait.k@...il.com>
> 
> Two tiny things inline.  
> 
> > +static int kx132_get_fifo_bytes(struct kx022a_data *data)
> > +{
> > +	struct device *dev = regmap_get_device(data->regmap);
> > +	__le16 buf_status;
> > +	int ret, fifo_bytes;
> > +
> > +	ret = regmap_bulk_read(data->regmap, data->chip_info->buf_status1,
> > +			       &buf_status, sizeof(buf_status));
> > +	if (ret) {
> > +		dev_err(dev, "Error reading buffer status\n");
> > +		return ret;
> > +	}
> > +
> > +	fifo_bytes = le16_to_cpu(buf_status);
> > +	fifo_bytes &= data->chip_info->buf_smp_lvl_mask;
> 
> Slight preference for FIELD_GET() as it saves me checking the mask includes
> lowest bits.

This will mean I have the remove the chip_info member buf_smp_lvl_mask
and use KX132_MASK_BUF_SMP_LVL directly because otherwise the
__builtin_constant_p function will cause an error when building. 
Check: https://elixir.bootlin.com/linux/latest/source/include/linux/bitfield.h#L65

I can change it to FIELD_GET() if you want to.

> 
> 
> > +
> > +	return fifo_bytes;
> > +}
> > +
> >  static int __kx022a_fifo_flush(struct iio_dev *idev, unsigned int samples,
> >  			       bool irq)
> >  {
> > @@ -1036,6 +1157,32 @@ const struct kx022a_chip_info kx022a_chip_info = {
> >  };
> >  EXPORT_SYMBOL_NS_GPL(kx022a_chip_info, IIO_KX022A);
> >  
> > +const struct kx022a_chip_info kx132_chip_info = {
> > +	.name		  = "kx132-1211",
> > +	.regmap_config	  = &kx132_regmap_config,
> > +	.channels	  = kx132_channels,
> > +	.num_channels	  = ARRAY_SIZE(kx132_channels),
> > +	.fifo_length	  = KX132_FIFO_LENGTH,
> > +	.who		  = KX132_REG_WHO,
> > +	.id		  = KX132_ID,
> > +	.cntl		  = KX132_REG_CNTL,
> > +	.cntl2		  = KX132_REG_CNTL2,
> > +	.odcntl		  = KX132_REG_ODCNTL,
> > +	.buf_cntl1	  = KX132_REG_BUF_CNTL1,
> > +	.buf_cntl2	  = KX132_REG_BUF_CNTL2,
> > +	.buf_clear	  = KX132_REG_BUF_CLEAR,
> > +	.buf_status1	  = KX132_REG_BUF_STATUS_1,
> > +	.buf_smp_lvl_mask = KX132_MASK_BUF_SMP_LVL,
> 
> There are some things in here (typically where the define isn't used
> anywhere else) where I think it would be easier to follow if the
> value was listed here.  Masks and IDs for example. 
> 

After removing buf_smp_lvl_mask, which members will be easier to understand (besides id) ? 

--
Kind Regards
Mehdi Djait