linux-kernel - Re: [PATCH v1] iio: adc: ad_sigma_delta: Clear pending interrupts before enable

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Date: Sat, 6 Apr 2024 17:17:28 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Markus Burri <markus.burri@...com>
Cc: linux-kernel@...r.kernel.org, Lars-Peter Clausen <lars@...afoo.de>,
 Michael Hennerich <Michael.Hennerich@...log.com>,
 linux-iio@...r.kernel.org, Nuno Sa <nuno.sa@...log.com>
Subject: Re: [PATCH v1] iio: adc: ad_sigma_delta: Clear pending interrupts
 before enable

On Thu,  4 Apr 2024 19:51:26 +0200
Markus Burri <markus.burri@...com> wrote:

Hi Markus,


> For device will enable and disable irq contiously like AD7195,
> it use DOUT/RDY pin for both SPI transfer and data ready.
> It will disable irq during SPI transfer, and re-eanble irq after SPI transfer.
> That may cause irq status bit set to 1 during spi transfer.

Superficially that sounds like it might be an irq driver bug to me...
Or just possibly an irq chip doing lazy disabling?

> 
> When the active condition has been detected, the corresponding bit
> remains set until cleared by software. Status flags are cleared
> by writing a 1 to the corresponding bit position.
> 
> Signed-off-by: Markus Burri <markus.burri@...com>

I'll need an appropriate ADI ack for this one.

It seems highly unusual to be calling a generic irqchip related function in a
driver (there are no other such users).  So this seems unlikely to be
the right fix for this particular problem.

> ---
>  drivers/iio/adc/ad_sigma_delta.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
> index a602429cdde4..59544c39642a 100644
> --- a/drivers/iio/adc/ad_sigma_delta.c
> +++ b/drivers/iio/adc/ad_sigma_delta.c
> @@ -515,6 +515,10 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
>  
>  irq_handled:
>  	iio_trigger_notify_done(indio_dev->trig);
> +	/*
> +	 * ACK pending interrupts from spi transfer.

Single line comment format would be fine here.

> +	 */
> +	irq_gc_ack_set_bit(irq_get_irq_data(sigma_delta->spi->irq));
>  	sigma_delta->irq_dis = false;
>  	enable_irq(sigma_delta->spi->irq);
>