linux-kernel - Re: [PATCH v5 3/3] iio: magnetometer: add ti tmag5273 driver

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Date:   Wed, 30 Nov 2022 19:43:05 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Gerald Loacker <gerald.loacker@...fvision.net>
Cc:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jakob Hauser <jahau@...ketmail.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Nikita Yushchenko <nikita.yoush@...entembedded.com>,
        Michael Riesch <michael.riesch@...fvision.net>
Subject: Re: [PATCH v5 3/3] iio: magnetometer: add ti tmag5273 driver

On Wed, Nov 30, 2022 at 05:32:10PM +0100, Gerald Loacker wrote:
> Am 30.11.2022 um 16:31 schrieb Andy Shevchenko:
> > On Wed, Nov 30, 2022 at 03:53:56PM +0100, Gerald Loacker wrote:

...

> >> +	switch (data->devid) {
> >> +	case TMAG5273_MANUFACTURER_ID:
> >> +		/*
> >> +		 * The device name matches the orderable part number. 'x' stands
> >> +		 * for A, B, C or D devices, which have different I2C addresses.
> >> +		 * Versions 1 or 2 (0 and 3 is reserved) stands for different
> >> +		 * magnetic strengths.
> >> +		 */
> >> +		snprintf(data->name, sizeof(data->name), "tmag5273x%1u", data->version);
> >> +		if (data->version < 1 || data->version > 2)
> >> +			dev_warn(data->dev, "Unsupported device %s\n", data->name);
> >> +		return 0;
> >> +	default:
> > 
> >> +		dev_warn(data->dev, "Unknown device ID 0x%x\n", data->devid);
> >> +		return 0;
> > 
> > And we still continue?! Wouldn't be a problem if that ID drastically changed in
> > terms of programming model and may actually be broken by a wrong sequence?
> 
> It was suggested by Jonathan to just print a warning instead of
> returning with -ENODEV. Reason was "Often manufacturers spin new
> versions of chips that are compatible enough that we give them a
> fallback compatible in device tree.". For me this makes sense.

Ah, I see. Maybe adding a comment summarizing above?

> >> +	}

-- 
With Best Regards,
Andy Shevchenko