linux-kernel - Re: [PATCH v2 2/3] iio: adc: ad7780: Fix IRQ flag

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Date:   Sat, 11 Sep 2021 18:45:44 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     <alexandru.tachici@...log.com>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] iio: adc: ad7780: Fix IRQ flag

On Mon, 6 Sep 2021 09:56:29 +0300
<alexandru.tachici@...log.com> wrote:

> From: Alexandru Tachici <alexandru.tachici@...log.com>
> 
> Correct IRQ flag here is falling.
> 
> In Sigma-Delta devices the SDO line is also used as an interrupt.
> Leaving IRQ on level instead of falling might trigger a sample read
> when the IRQ is enabled, as the SDO line is already low. Not sure
> if SDO line will always imediately go high in ad_sd_buffer_postenable
> before the IRQ is enabled.
> 
> Also the datasheet seem to explicitly say the falling edge of the SDO
> should be used as an interrupt:
> From the AD7780 datasheet: " The DOUT/Figure 22 RDY falling edge
> can be used as an interrupt to a processor"
> 
> Fixes: da4d3d6bb9f6 ("iio: adc: ad-sigma-delta: Allow custom IRQ flags")
> Signed-off-by: Alexandru Tachici <alexandru.tachici@...log.com>
Applied and marked for stable.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/ad7780.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/ad7780.c b/drivers/iio/adc/ad7780.c
> index 42bb952f4738..b6e8c8abf6f4 100644
> --- a/drivers/iio/adc/ad7780.c
> +++ b/drivers/iio/adc/ad7780.c
> @@ -203,7 +203,7 @@ static const struct ad_sigma_delta_info ad7780_sigma_delta_info = {
>  	.set_mode = ad7780_set_mode,
>  	.postprocess_sample = ad7780_postprocess_sample,
>  	.has_registers = false,
> -	.irq_flags = IRQF_TRIGGER_LOW,
> +	.irq_flags = IRQF_TRIGGER_FALLING,
>  };
>  
>  #define _AD7780_CHANNEL(_bits, _wordsize, _mask_all)		\