linux-kernel - Re: [PATCH v10 2/5] regulator: hi6421v600-regulator: fix platform drvdata

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Date:   Tue, 29 Jun 2021 21:31:56 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linuxarm@...wei.com, mauro.chehab@...wei.com,
        Axel Lin <axel.lin@...ics.com>,
        Lee Jones <lee.jones@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Liam Girdwood <lgirdwood@...il.com>,
        linux-kernel@...r.kernel.org, linux-staging@...ts.linux.dev
Subject: Re: [PATCH v10 2/5] regulator: hi6421v600-regulator: fix platform
 drvdata

Em Tue, 29 Jun 2021 16:11:01 +0100
Mark Brown <broonie@...nel.org> escreveu:

> On Tue, Jun 29, 2021 at 12:31:28PM +0200, Mauro Carvalho Chehab wrote:
> 
> > platform drvdata can't be used inside the regulator driver,
> > as this is already used by the MFD and SPMI drivers.  
> 
> Can you clarify what exactly is using which platform drvdata already?
> This all feels very confused and I can't tell what the problem that's
> being fixed is, if it's a real issue or how this fixes it.

I don't remember the dirty details anymore... It has been almost a year
since when I started doing that. The SPMI controller driver left staging
8 months ago.

I guess it is related with passing the parent's device to
devm_regulator_register() at the hi6421v600-regulator driver:

	struct regulator_config config = { };
...
	config.dev = pdev->dev.parent;
...
	rdev = devm_regulator_register(dev, &info->desc, &config);

This is needed by SPMI bus and the SPMI controller in order to use the 
right platform data when talking to the hardware.

> >  drivers/misc/hi6421v600-irq.c               |  9 ++--
> >  drivers/regulator/hi6421v600-regulator.c    | 49 +++++++++++----------
> >  drivers/staging/hikey9xx/hi6421-spmi-pmic.c | 18 +++-----
> >  include/linux/mfd/hi6421-spmi-pmic.h        | 25 -----------  
> 
> I'm especially nervous about the core driver still being in staging
> perhaps meaning there's some issue with it doing odd and confusing
> things.

The only missing part in staging is the MFD driver. At the current way,
it is very simple (71 lines in total): it just declares a regmap, and has 
a single function on it:

	static int hi6421_spmi_pmic_probe(struct spmi_device *pdev)
	{
		struct device *dev = &pdev->dev;
		int ret;
		struct hi6421_spmi_pmic *ddata;
		ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
		if (!ddata)
			return -ENOMEM;
	
		ddata->regmap = devm_regmap_init_spmi_ext(pdev, &regmap_config);
		if (IS_ERR(ddata->regmap))
			return PTR_ERR(ddata->regmap);
	
		ddata->dev = dev;
	
		dev_set_drvdata(&pdev->dev, ddata);

		ret = devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
					   hi6421v600_devs, ARRAY_SIZE(hi6421v600_devs),
					   NULL, 0, NULL);
		if (ret < 0)
			dev_err(dev, "Failed to add child devices: %d\n", ret);

		return ret;
	}

You can see the full driver's code at:
	https://lore.kernel.org/lkml/8d871e2ccc544d11959c16d8312dbf03dd01b1c8.1624962269.git.mchehab+huawei@kernel.org/#Z30drivers:mfd:hi6421-spmi-pmic.c

I'm not aware of anything left preventing it to leave staging.

Thanks,
Mauro