linux-kernel - Re: [PATCH v2] iio: adc: ad7944: Add support for "3-wire mode"

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Date: Mon, 18 Mar 2024 09:33:44 -0500
From: David Lechner <dlechner@...libre.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Jonathan Cameron <jic23@...nel.org>, Michael Hennerich <michael.hennerich@...log.com>, 
	Nuno Sá <nuno.sa@...log.com>, linux-iio@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: adc: ad7944: Add support for "3-wire mode"

On Sun, Mar 17, 2024 at 3:23 AM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Sun, Mar 17, 2024 at 1:10 AM David Lechner <dlechner@...libre.com> wrote:
> > On Sat, Mar 16, 2024 at 2:57 PM Andy Shevchenko
> > <andy.shevchenko@...il.com> wrote:
> > > Thu, Mar 14, 2024 at 12:43:38PM -0500, David Lechner kirjoitti:
>

..

> > > > +     case AD7944_SPI_MODE_SINGLE:
> > > > +             ret = ad7944_3wire_cs_mode_conversion(adc, &indio_dev->channels[0]);
> > > > +             if (ret)
> > > > +                     goto out;
> > > > +
> > > > +             break;
> > > > +     default:
> > > > +             /* not supported */
> > >
> > > No error code set?
> >
> > This is in an interrupt handler, so I didn't think there was anything
> > we can do with an error.
>
> return IRQ_NONE?
>

Wouldn't this just cause the interrupt handler to trigger again
immediately resulting in very high CPU load? I don't see any other IIO
ADC drivers using the generic triggered buffer returning anything
other than IRQ_HANDLED and I always assumed this was the reason.