linux-kernel - Re: [RFT v3 06/14] regulator: max77802: Remove support for board files

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Date:	Thu, 30 Oct 2014 13:53:07 +0100
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
	Ben Dooks <ben-linux@...ff.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Chanwoo Choi <cw00.choi@...sung.com>
Subject: Re: [RFT v3 06/14] regulator: max77802: Remove support for board files

On czw, 2014-10-30 at 13:42 +0100, Javier Martinez Canillas wrote:
> Hello Krzysztof,
> 
> On 10/30/2014 01:30 PM, Krzysztof Kozlowski wrote:
> tor_of_get_init_data() function?
> >> > 
> >> > The regulator_of_get_init_data() searches from dev->of_node or its child
> >> > node.
> >> > 
> >> > But dev->of_node is NULL.
> >> > 
> >> > That's why of_compatible is needed.
> >> 
> >> Yes but regulator_register() does dev = config->dev and config->dev is set
> >> to config.dev = iodev->dev in the driver probe function which is the
> >> pdev->dev.parent (the PMIC struct device) that has an associated of_node.
> >> 
> >> So, regulator_of_get_init_data() will call of_get_child_by_name() passing
> >> the PMIC of_node and the sub-node name that contains the regulators. That
> >> is, whatever was set in desc->regulators_node and that should be enough.
> > 
> > I missed that one in max77802 (in max77686: config.dev = &pdev->dev).
> > Now I wonder if it is proper to attach regulators to driver's parent
> > device. Consider regulator_register, around line 3640:
> > 	rdev->dev.parent = dev;
> > The parent of regulators will be equal to parent of regulator driver -
> > main MFD driver.
> >
> 
> An early version of the max77802 regulator driver also set config.dev to
> &pdev->dev but then Mark asked me if I was sure that it should not be the
> MFD device instead.
> 
> I then read in regulator_register() that the rdev->dev.parent was set
> to the device passed in config.dev as you said so I was convinced that it
> should be the parent device instead.
> 
> Please take a look at [0] for that discussion.

To me a intuitive structure would be:
MFD device
  |
  - clock device
     |
     - clock1
     - clock2
  - regulator device
     |
     - LDO1
     - LDO2
etc.

This also maps to structure in DTS. dev_err* messages and any
allocations should be done on behalf of regulator device, not parent.

Various drivers do this differently... The wm8* drivers set it mostly to
parent (MFD)...

I do not insists, especially because using parent's device would make
this driver simpler.

Mark, maybe you could shed light on it?


Best regards,
Krzysztof


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