linux-kernel - Re: [PATCH v4] Fix IRQ issue by setting IRQ_DISABLE

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Date:   Wed, 03 May 2023 10:09:28 +0200
From:   Nuno Sá <noname.nuno@...il.com>
To:     Masahiro Honda <honda@...hatrax.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] Fix IRQ issue by setting IRQ_DISABLE_UNLAZY flag

On Tue, 2023-05-02 at 19:29 +0900, Masahiro Honda wrote:
> The Sigma-Delta ADCs supported by this driver can use SDO as an interrupt
> line to indicate the completion of a conversion. However, some devices
> cannot properly detect the completion of a conversion by an interrupt.
> This is for the reason mentioned in the following commit.
> 
> commit e9849777d0e2 ("genirq: Add flag to force mask in
>                       disable_irq[_nosync]()")
> 
> A read operation is performed by an extra interrupt before the completion
> of a conversion. This patch fixes the issue by setting IRQ_DISABLE_UNLAZY
> flag.
> 
> Signed-off-by: Masahiro Honda <honda@...hatrax.com>
> ---

Reviewed-by: Nuno Sá <nuno.sa@...log.com>

> v4:
>  - Remove the callback.
> v3:
> https://lore.kernel.org/linux-iio/20230420102316.757-1-honda@mechatrax.com/
>  - Remove the Kconfig option.
> v2:
> https://lore.kernel.org/linux-iio/20230414102744.150-1-honda@mechatrax.com/
>  - Rework commit message.
>  - Add a new entry in the Kconfig.
>  - Call irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY) when freeing the IRQ.
> v1:
> https://lore.kernel.org/linux-iio/20230306044737.862-1-honda@mechatrax.com/
> 
>  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 d8570f6207..7e21928707 100644
> --- a/drivers/iio/adc/ad_sigma_delta.c
> +++ b/drivers/iio/adc/ad_sigma_delta.c
> @@ -584,6 +584,10 @@ static int devm_ad_sd_probe_trigger(struct device *dev,
> struct iio_dev *indio_de
>         init_completion(&sigma_delta->completion);
>  
>         sigma_delta->irq_dis = true;
> +
> +       /* the IRQ core clears IRQ_DISABLE_UNLAZY flag when freeing an IRQ */
> +       irq_set_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZY);
> +
>         ret = devm_request_irq(dev, sigma_delta->spi->irq,
>                                ad_sd_data_rdy_trig_poll,
>                                sigma_delta->info->irq_flags | IRQF_NO_AUTOEN,