linux-kernel - Re: [PATCH V2] iio: ad_sigma

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Date:   Sat, 11 Jan 2020 11:23:17 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Tachici <alexandru.tachici@...log.com>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2] iio: ad_sigma_delta: Add custom irq flags

On Tue, 7 Jan 2020 13:06:36 +0200
Alexandru Tachici <alexandru.tachici@...log.com> wrote:

> The data-sheet of AD7124, from the Sigma-Delta ADC family,
> recommends that the falling edge of the DOUT line should be used for
> an interrupt.
> 
> The ad_sigma_delta implementation hardcodes the irq trigger type
> to low, assuming that all Sigma-Delta ADCs have the same interrupt-type.
> This causes unwanted behaviour. If DOUT line is already low, the
> interrupt will fire once, when enabled and the irq handler will send a
> read request to the device. At this time the device has not yet finished
> the previous conversion and will give a bad reading.
> 
> This patch allows drivers using the ad_sigma_delta layer to set the
> irq trigger type to the one specified in the corresponding data-sheet.
> 
> Signed-off-by: Alexandru Tachici <alexandru.tachici@...log.com>

Hi Alexandru.

Patch is fine, but I'd expect to see it in a series with the change
for the ad7124 driver.  I'm never keen to merge new features without
a user.  So send a v3, with the change to that driver (which I'm guessing
is pretty trivial!)

Thanks,

Jonathan

> ---
> Changelog V1-V2:
>  - added a V2 tag
> 
>  drivers/iio/adc/ad_sigma_delta.c       | 9 ++++++++-
>  include/linux/iio/adc/ad_sigma_delta.h | 2 ++
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
> index d10bd0c97233..0007df8d50fb 100644
> --- a/drivers/iio/adc/ad_sigma_delta.c
> +++ b/drivers/iio/adc/ad_sigma_delta.c
> @@ -454,7 +454,7 @@ static int ad_sd_probe_trigger(struct iio_dev *indio_dev)
>  
>  	ret = request_irq(sigma_delta->spi->irq,
>  			  ad_sd_data_rdy_trig_poll,
> -			  IRQF_TRIGGER_LOW,
> +			  sigma_delta->irq_flags,
>  			  indio_dev->name,
>  			  sigma_delta);
>  	if (ret)
> @@ -540,8 +540,15 @@ EXPORT_SYMBOL_GPL(ad_sd_cleanup_buffer_and_trigger);
>  int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
>  	struct spi_device *spi, const struct ad_sigma_delta_info *info)
>  {
> +	unsigned long set_trigger_flags;
> +
>  	sigma_delta->spi = spi;
>  	sigma_delta->info = info;
> +
> +	set_trigger_flags = sigma_delta->irq_flags & IRQF_TRIGGER_MASK;
> +	if (set_trigger_flags == IRQF_TRIGGER_NONE)
> +		sigma_delta->irq_flags |= IRQF_TRIGGER_LOW;
> +
>  	iio_device_set_drvdata(indio_dev, sigma_delta);
>  
>  	return 0;
> diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h
> index 5ba430cc9a87..94a91731c8e8 100644
> --- a/include/linux/iio/adc/ad_sigma_delta.h
> +++ b/include/linux/iio/adc/ad_sigma_delta.h
> @@ -53,6 +53,7 @@ struct ad_sigma_delta_info {
>   * struct ad_sigma_delta - Sigma Delta device struct
>   * @spi: The spi device associated with the Sigma Delta device.
>   * @trig: The IIO trigger associated with the Sigma Delta device.
> + * @irq_flags: flags for the interrupt used by the triggered buffer
>   *
>   * Most of the fields are private to the sigma delta library code and should not
>   * be accessed by individual drivers.
> @@ -60,6 +61,7 @@ struct ad_sigma_delta_info {
>  struct ad_sigma_delta {
>  	struct spi_device	*spi;
>  	struct iio_trigger	*trig;
> +	unsigned long		irq_flags;
>  
>  /* private: */
>  	struct completion	completion;