linux-kernel - Re: [PATCH v4 5/5] iio: adc: ad7606: add gain calibration support

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Message-ID: <aCsEeQQyGdBg2ex9@smile.fi.intel.com>
Date: Mon, 19 May 2025 13:14:17 +0300
From: Andy Shevchenko <andy@...nel.org>
To: Angelo Dureghello <adureghello@...libre.com>
Cc: Jonathan Cameron <jic23@...nel.org>,
	David Lechner <dlechner@...libre.com>,
	Nuno Sá <nuno.sa@...log.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Michael Hennerich <Michael.Hennerich@...log.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v4 5/5] iio: adc: ad7606: add gain calibration support

On Mon, May 19, 2025 at 11:40:09AM +0200, Angelo Dureghello wrote:
> On 08.05.2025 22:00, Andy Shevchenko wrote:
> > On Thu, May 08, 2025 at 12:06:09PM +0200, Angelo Dureghello wrote:

...

> > > +	device_for_each_child_node_scoped(dev, child) {
> > > +		u32 reg, r_gain;
> > > +
> > > +		ret = fwnode_property_read_u32(child, "reg", &reg);
> > > +		if (ret)
> > > +			continue;
> > 
> > > +		/* Chan reg is a 1-based index. */
> > > +		if (reg < 1 || reg > num_channels) {
> > > +			dev_warn(dev, "wrong ch number (ignoring): %d\n", reg);
> > > +			continue;
> > > +		}
> > 
> > But this will allow to have a broken DT. This check basically diminishes the
> > effort of the DT schema validation. If there are limits one still would be able
> > to create a DT that passes the driver but doesn't pass the validation.
> 
> fixed all your points on other patches of this patch-set. Still your
> emails are going to google spam, just could catch them on friday. 
> Really not clear why.

DKIM which I still need to configure...

> About the above, i understand, but the check is actually the same as
> in ad7606_get_chan_config(), a warning that fdt is not correct, 
> i dont see a blocking issue here now, so not going to change it
> in this next patchset.

I think the 'continue' above is simply wrong. We should not allow to have
broken tables. And I think it's kinda blocking issue.

> > > +		ret = fwnode_property_read_u32(child, "adi,rfilter-ohms",
> > > +					       &r_gain);
> > > +		if (ret)
> > > +			/* Keep the default register value. */
> > > +			continue;
> > > +
> > > +		if (r_gain > AD7606_CALIB_GAIN_MAX) {
> > > +			dev_warn(dev, "wrong gain calibration value");
> > > +			continue;
> > > +		}
> > > +
> > > +		ret = st->bops->reg_write(st, AD7606_CALIB_GAIN(reg - 1),
> > > +			DIV_ROUND_CLOSEST(r_gain, AD7606_CALIB_GAIN_STEP));
> > > +		if (ret) {
> > > +			dev_warn(dev, "error writing r_gain");
> > > +			continue;
> > > +		}
> > > +	}

-- 
With Best Regards,
Andy Shevchenko