linux-kernel - Re: [PATCH 5/6] iio: pressure: hsc030pa add triggered buffer

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Message-ID: <20240112170924.000040af@Huawei.com>
Date: Fri, 12 Jan 2024 17:09:24 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Petre Rodan <petre.rodan@...dimension.ro>
CC: <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Jonathan
 Cameron" <jic23@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>
Subject: Re: [PATCH 5/6] iio: pressure: hsc030pa add triggered buffer

On Wed, 10 Jan 2024 19:22:40 +0200
Petre Rodan <petre.rodan@...dimension.ro> wrote:

> Add triggered buffer feature.
> 
> Signed-off-by: Petre Rodan <petre.rodan@...dimension.ro>
Hi Petre,

A few minor things inline. + you almost certainly need some Kconfig
changes to ensure buffered support is built for the IIO core.

> ---
>  drivers/iio/pressure/hsc030pa.c | 42 +++++++++++++++++++++++++++++++++
>  drivers/iio/pressure/hsc030pa.h |  2 +-
>  2 files changed, 43 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/pressure/hsc030pa.c b/drivers/iio/pressure/hsc030pa.c
> index 7e3f74d53b47..3faa0fd42201 100644
> --- a/drivers/iio/pressure/hsc030pa.c
> +++ b/drivers/iio/pressure/hsc030pa.c
> @@ -22,8 +22,11 @@
>  #include <linux/types.h>
>  #include <linux/units.h>
> 
> +#include <linux/iio/buffer.h>
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> 
>  #include <asm/unaligned.h>
> 
> @@ -297,6 +300,23 @@ static int hsc_get_measurement(struct hsc_data *data)
>  	return 0;
>  }
> 
> +static irqreturn_t hsc_trigger_handler(int irq, void *private)
> +{
> +	struct iio_poll_func *pf = private;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct hsc_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = hsc_get_measurement(data);
> +	if (!ret) {
Prefer error handling out of line + no {} for single statements

	if (ret)
		goto error;

	iio_push...

error:
	iio_trigger...

> +		iio_push_to_buffers_with_timestamp(indio_dev, &data->buffer,
> +						   iio_get_time_ns(indio_dev));
> +	}
> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  /*
>   * IIO ABI expects
>   * value = (conv + offset) * scale
> @@ -382,13 +402,30 @@ static const struct iio_chan_spec hsc_channels[] = {
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>  				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OFFSET),
> +		.scan_index = 0,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 14,
> +			.storagebits = 16,
> +			.shift = 0,

No need to specify shift if it's zero. That's considered the obvious default
and C will ensure it's set to 0 anyway.

> +			.endianness = IIO_BE,
> +		},
>  	},
>  	{
>  		.type = IIO_TEMP,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>  				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OFFSET),
> +		.scan_index = 1,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 11,
> +			.storagebits = 16,
> +			.shift = 5,
> +			.endianness = IIO_BE,
> +		},
>  	},
> +	IIO_CHAN_SOFT_TIMESTAMP(2),
>  };
> 
>  static const struct iio_info hsc_info = {
> @@ -485,6 +522,11 @@ int hsc_common_probe(struct device *dev, hsc_recv_fn recv)
>  	indio_dev->channels = hsc->chip->channels;
>  	indio_dev->num_channels = hsc->chip->num_channels;
> 
> +	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> +					      hsc_trigger_handler, NULL);
> +	if (ret)
> +		return ret;
> +
>  	return devm_iio_device_register(dev, indio_dev);
>  }
>  EXPORT_SYMBOL_NS(hsc_common_probe, IIO_HONEYWELL_HSC030PA);
> diff --git a/drivers/iio/pressure/hsc030pa.h b/drivers/iio/pressure/hsc030pa.h
> index 56dc8e88194b..6c635c42d85d 100644
> --- a/drivers/iio/pressure/hsc030pa.h
> +++ b/drivers/iio/pressure/hsc030pa.h
> @@ -56,7 +56,7 @@ struct hsc_data {
>  	s32 p_scale_dec;
>  	s64 p_offset;
>  	s32 p_offset_dec;
> -	u8 buffer[HSC_REG_MEASUREMENT_RD_SIZE] __aligned(IIO_DMA_MINALIGN);
> +	u8 buffer[16] __aligned(IIO_DMA_MINALIGN);

Justify that size.  Normal trick is to use a suitable structure definition with
the channels and a timestamp s64 with force alignment (To deal with te annoying 
x86 32bit alignment)

>  };
> 
>  struct hsc_chip_data {
> --
> 2.41.0
> 
>