linux-kernel - Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device Tree

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Message-ID: <20170105074952.GG24225@dell>
Date:   Thu, 5 Jan 2017 07:49:52 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Richard Purdie <rpurdie@...ys.net>,
        Jacek Anaszewski <j.anaszewski@...sung.com>,
        Pavel Machek <pavel@....cz>, Jingoo Han <jingoohan1@...il.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-leds@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...ymobile.com>
Subject: Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device
 Tree

On Wed, 04 Jan 2017, Bjorn Andersson wrote:

> On Wed 04 Jan 03:54 PST 2017, Lee Jones wrote:
> 
> > On Mon, 26 Dec 2016, Bjorn Andersson wrote:
> > 
> > > From: Bjorn Andersson <bjorn.andersson@...ymobile.com>
> > > 
> > > Implement support for initialization of the lm3533 driver core and
> > > probing child devices from Device Tree.
> > > 
> 
> [..]
> 
> > > @@ -512,6 +514,11 @@ static int lm3533_device_init(struct lm3533 *lm3533)
> > >  	lm3533_device_bl_init(lm3533);
> > >  	lm3533_device_led_init(lm3533);
> > >  
> > > +	if (lm3533->dev->of_node) {
> > > +		of_platform_populate(lm3533->dev->of_node, NULL, NULL,
> > > +				     lm3533->dev);
> > > +	}
> > 
> > I think it's save to call of_platform_populate(), even if !of_node.
> > It will just fail and return an error code, which you are ignoring
> > anyway.
> > 
> 
> I thought so too, but that's apparently how you trigger probing children
> of the root node. So we're stuck with a conditional.

Ah, so this is to protect against the case where DT is present, but a
node for this device is not (or is disabled), so is left unprobed.
Then the bind is initiated via I2C?  Or something else?

> > >  static int lm3533_i2c_probe(struct i2c_client *i2c,
> > >  					const struct i2c_device_id *id)
> > >  {
> 
> [..]
> 
> > >  
> > > +	if (i2c->dev.of_node) {
> > 
> > I'd prefer this check to be placed in lm3533_pdata_from_of_node().
> > 
> > Just return silently if !dev->of_node.
> > 
> 
> I agree, will update this.
> 
> > > +		ret = lm3533_pdata_from_of_node(lm3533->dev);
> > > +		if (ret < 0)
> > > +			return ret;
> > > +	}
> > > +
> > >  	return lm3533_device_init(lm3533);
> > >  }
> > >  
> 
> Regards,
> Bjorn

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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