linux-kernel - Re: [PATCH 2/2] iio: adc: imx93: Make calibration parameters configurable

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Message-ID: <aG-v9IxJ-XAxmnyh@smile.fi.intel.com>
Date: Thu, 10 Jul 2025 15:20:04 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Primoz Fiser <primoz.fiser@...ik.com>
Cc: Haibo Chen <haibo.chen@....com>, Jonathan Cameron <jic23@...nel.org>,
	David Lechner <dlechner@...libre.com>, Nuno Sa <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>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, linux-iio@...r.kernel.org,
	imx@...ts.linux.dev, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	upstream@...ts.phytec.de, andrej.picej@...ik.com
Subject: Re: [PATCH 2/2] iio: adc: imx93: Make calibration parameters
 configurable

On Thu, Jul 10, 2025 at 12:23:58PM +0200, Primoz Fiser wrote:
> On 10. 07. 25 11:22, Andy Shevchenko wrote:
> > On Thu, Jul 10, 2025 at 09:39:04AM +0200, Primoz Fiser wrote:

...

> >> +	ret = device_property_read_u32(adc->dev, "nxp,calib-avg-en", &val);
> >> +	if (!ret) {
> >> +		if (val != 0 && val != 1) {
> >> +			dev_err(adc->dev, "invalid nxp,calib-avg-en: %d\n", val);
> >> +			return -EINVAL;
> >> +		}
> >> +		reg = val;
> >> +		mcr &= ~IMX93_ADC_MCR_AVGEN_MASK;
> >> +		mcr |= FIELD_PREP(IMX93_ADC_MCR_AVGEN_MASK, reg);
> >> +	}
> > 
> > Please, since it's optional, do other way around.
> > 
> > 	val = $DEFAUTL;
> > 	device_property_read_u32(adc->dev, "nxp,calib-avg-en", &val);
> > 	FIELD_MODIFY(...)
> > 
> > Similar approach may be used for the other properties.
> 
> OK, I guess I could implement it like you suggested to explicitly set
> the default parameter values.
> 
> But in current implementation MCR values are read at the beginning of
> imx93_adc_calibration(), meaning calibration parameters are register POR
> defaults. With you suggestion, we put defaults in software rather than
> reading them from the hw directly.

I see, then you need to read, do FIELD_GET()/device_property_read()/FIELD_MODIFY().
You got the idea.

...

> > Please, factor out this to the function, so we won't see the direct IO in the
> > ->probe().
> 
> Sorry I don't understand this part.
> 
> What do you mean by factoring out this writel()?
> 
> Do you perhaps suggest to implement function
> imx93_adc_configure_calibration() and put all our changes into it?
> 
> But we are already in imx93_adc_calibration() which is separate from
> probe().

Ah, sorry for the mistakenly read the function name. Ignore this comment.

-- 
With Best Regards,
Andy Shevchenko