linux-kernel - Re: [PATCH v3 3/5] drivers: regulator: Add ADI MAX77541/MAX77540 Regulator Support

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Message-ID: <Y9kXxP/cEBJ5gyoB@smile.fi.intel.com>
Date:   Tue, 31 Jan 2023 15:29:40 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     "Sahin, Okan" <Okan.Sahin@...log.com>
Cc:     Lee Jones <lee@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        ChiYuan Huang <cy_huang@...htek.com>,
        "Bolboaca, Ramona" <Ramona.Bolboaca@...log.com>,
        Caleb Connolly <caleb.connolly@...aro.org>,
        William Breathitt Gray <william.gray@...aro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: [PATCH v3 3/5] drivers: regulator: Add ADI MAX77541/MAX77540
 Regulator Support

On Tue, Jan 31, 2023 at 01:23:33PM +0000, Sahin, Okan wrote:
> On Tue, 31 Jan 2022 3:27 PM
> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> >On Tue, Jan 31, 2023 at 09:27:48AM +0000, Sahin, Okan wrote:

...

> >> Sorry for second question. I do not want to bother you, but I realized
> >> that I need to be sure about driver_data before sending new patch. You
> >> said that you need to use pointers directly for driver_data then I
> >> fixed that part in mfd, but I do not need or  use driver_data in
> >> regulator since chip_id comes from mfd device so I think using like
> >> below should be enough for my implementation.
> >>
> >> static const struct platform_device_id max77541_regulator_platform_id[] = {
> >> 	{ "max77540-regulator", },
> >> 	{ "max77541-regulator", },
> >> 	{  /* sentinel */  }
> >> };
> >> MODULE_DEVICE_TABLE(platform, max77541_regulator_platform_id);
> >>
> >> static const struct of_device_id max77541_regulator_of_id[] = {
> >> 	{ .compatible = "adi,max77540-regulator", },
> >> 	{ .compatible = "adi,max77541-regulator", },
> >> 	{ /* sentinel */  }
> >> };
> >> MODULE_DEVICE_TABLE(of, max77541_regulator_of_id);
> >>
> >> What do you think?
> >
> >If you have got all necessary data from the upper layer, why do you need to have
> >an ID table here? I'm not sure I understand how this OF ID table works in this
> >case.

> I added it since there is regulator node in device tree. With the help of
> devm_regulator_register(..), driver takes parameters of regulator node. I
> also used id to select and to initialize regulator descriptors which are chip
> specific. So far there is no comment about OF ID table so I kept it. I
> thought I need to add both of id table and platform id table as name matching
> is required to initialize platform device from mfd.

For platform device is one mechanism how to enumerate device, and bind it to
the driver. The OF ID table needs to be present in case you are using it for
direct DT enumeration (there is also something related to MFD child nodes, but
you need to check and explain how your device is enumerated by this driver).

I.o.w. please clarify how the OF ID table is being used.

-- 
With Best Regards,
Andy Shevchenko