linux-kernel - Re: [PATCH 7/8] iio: adc: ad7476: Support ROHM BD79105

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Message-ID: <CAHp75VfsCHJtrueAVQdbwUjLBCo_kRKVfifUgVrhicvXftPrDQ@mail.gmail.com>
Date: Thu, 7 Aug 2025 23:08:46 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Andy Shevchenko <andriy.shevchenko@...el.com>, 
	Matti Vaittinen <matti.vaittinen@...rohmeurope.com>, Lars-Peter Clausen <lars@...afoo.de>, 
	Michael Hennerich <Michael.Hennerich@...log.com>, Jonathan Cameron <jic23@...nel.org>, 
	David Lechner <dlechner@...libre.com>, Nuno Sá <nuno.sa@...log.com>, 
	Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, linux-iio@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/8] iio: adc: ad7476: Support ROHM BD79105

On Thu, Aug 7, 2025 at 9:31 AM Matti Vaittinen <mazziesaccount@...il.com> wrote:
> On 06/08/2025 23:26, Andy Shevchenko wrote:
> > On Wed, Aug 06, 2025 at 10:04:43AM +0300, Matti Vaittinen wrote:

...

> >> +static void bd79105_convst_enable(struct ad7476_state *st)
> >> +{
> >
> >> +    if (!st->convst_gpio)
> >> +            return;
> >
> > With 10ns sleep in mind this is also unneeded check.
> >
> >> +    gpiod_set_value(st->convst_gpio, 1);
> >
> >> +    udelay(1); /* 10ns required for conversion */
> >
> > We have ndelay(). But I believe toggling GPIO is much longer operation.
>
> Thanks for the review Andy.
>
> As I replied to David, this 10nS is rubbish. I need to clarify the right
> value.

Then probably you want to call fsleep(), and if the value is few /
dozens of useconds, I would drop the check for GPIO and leave with a
small delay.

-- 
With Best Regards,
Andy Shevchenko