Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230502102930.773-1-honda@mechatrax.com> <f83adfd4df5cd23176721087a4fcd9a0225c3483.camel@gmail.com>
 <20230507160104.1d6e8bb8@jic23-huawei>
In-Reply-To: <20230507160104.1d6e8bb8@jic23-huawei>
From:   Masahiro Honda <honda@mechatrax.com>
Date:   Mon, 8 May 2023 18:45:36 +0900
Message-ID: <CA+Tz-SHF9+GxVD+U88tTxG4LYCC9BXSQKpVHL3E0eni+fRrgkQ@mail.gmail.com>
Subject: Re: [PATCH v4] Fix IRQ issue by setting IRQ_DISABLE_UNLAZY flag
To:     Jonathan Cameron <jic23@kernel.org>
Cc:     =?UTF-8?B?TnVubyBTw6E=?= <noname.nuno@gmail.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Michael Hennerich <Michael.Hennerich@analog.com>,
        linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Hi Jonathan,

Thank you for your advice.

On Sun, May 7, 2023 at 11:45=E2=80=AFPM Jonathan Cameron <jic23@kernel.org>=
 wrote:
>
> On Wed, 03 May 2023 10:09:28 +0200
> Nuno S=C3=A1 <noname.nuno@gmail.com> wrote:
>
> Patch title should be something like the following so it's easy to see wh=
at
> is affected when looking at a long list of patches.
>
> iio: adc: ad_sigma_delta: Fix IRQ issue by setting IRQ_DISABLE_UNLAZY fla=
g.
>

I'll fix the title.

>
> > 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 inter=
rupt
> > > line to indicate the completion of a conversion. However, some device=
s
> > > 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 comple=
tion
> > > of a conversion. This patch fixes the issue by setting IRQ_DISABLE_UN=
LAZY
> > > flag.
> > >
> > > Signed-off-by: Masahiro Honda <honda@mechatrax.com>
> > > ---
> >
> > Reviewed-by: Nuno S=C3=A1 <nuno.sa@analog.com>
>
> Fixes tag?  We'll want to know how far to backport this.  I assume it's
> limited by the above commit as these drivers are older than that.
>

I'll try to add a fixes tag.

> I'm also not totally sure what this 'looks like' for a user.  What happen=
s?
> Fail to read, wrong value, lock up or something else?  It would be helpfu=
l
> to include that information in case anyone else runs into this.
>

I'll add information to the commit message.

Regards,

Masahiro


> Actual change looks right to me.
>
> Thanks,
>
> Jonathan
>
>
> >
> > > v4:
> > >  - Remove the callback.
> > > v3:
> > > https://lore.kernel.org/linux-iio/20230420102316.757-1-honda@mechatra=
x.com/
> > >  - Remove the Kconfig option.
> > > v2:
> > > https://lore.kernel.org/linux-iio/20230414102744.150-1-honda@mechatra=
x.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@mechatra=
x.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 devic=
e *dev,
> > > struct iio_dev *indio_de
> > >         init_completion(&sigma_delta->completion);
> > >
> > >         sigma_delta->irq_dis =3D true;
> > > +
> > > +       /* the IRQ core clears IRQ_DISABLE_UNLAZY flag when freeing a=
n IRQ */
> > > +       irq_set_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZ=
Y);
> > > +
> > >         ret =3D devm_request_irq(dev, sigma_delta->spi->irq,
> > >                                ad_sd_data_rdy_trig_poll,
> > >                                sigma_delta->info->irq_flags | IRQF_NO=
_AUTOEN,
> >
>