linux-kernel - Re: [PATCH 1/3] regulator: max14577: Add proper dt-compatible strings

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Message-ID: <964b8c4c-36ca-203d-e62b-4a8fc970e23d@samsung.com>
Date:   Fri, 21 Feb 2020 11:44:03 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Sebastian Reichel <sre@...nel.org>
Subject: Re: [PATCH 1/3] regulator: max14577: Add proper dt-compatible
 strings

Hi Mark,

On 20.02.2020 17:56, Mark Brown wrote:
> On Thu, Feb 20, 2020 at 03:51:25PM +0100, Marek Szyprowski wrote:
>> Add device tree compatible strings and create proper modalias structures
>> to let this driver load automatically if compiled as module, because
>> max14577 MFD driver creates MFD cells with such compatible strings.
>> +static const struct of_device_id of_max14577_regulator_dt_match[] = {
>> +	{ .compatible = "maxim,max77836-regulator",
>> +	  .data = (void *)MAXIM_DEVICE_TYPE_MAX77836, },
>> +	{ .compatible = "maxim,max14577-regulator",
>> +	  .data = (void *)MAXIM_DEVICE_TYPE_MAX14577, },
> Why would we want to encode the particular way Linux happens to
> represent regulators on a MFD into the DT binding?  It's not clear that
> this is a generic thing (another OS might choose to have a separate
> object for each regulator with no parent for example) and the compatible
> isn't adding any information we didn't have already knowing about the
> parent device.

Well, that's how the bindings for max14577/max77836 are defined:

Documentation/devicetree/bindings/mfd/max14577.txt

I've only fixed regulator, charger and extcon drivers to match the cells 
created by the current mfd driver.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland