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

From Bjorn Andersson <bjorn.andersson@linaro.org>
Newsgroups linux.kernel
Subject Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device Tree
Date 2017-01-05 17:40 +0100
Message-ID <sWjf3-5uZ-11@gated-at.bofh.it> (permalink)
References <sSPwR-4qF-3@gated-at.bofh.it> <sSPwR-4qF-5@gated-at.bofh.it> <sVSyd-4tG-1@gated-at.bofh.it> <sVZq1-vQ-15@gated-at.bofh.it> <sWaY9-8ch-5@gated-at.bofh.it>
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On Wed 04 Jan 23:49 PST 2017, Lee Jones wrote:

> 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@sonymobile.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?
> 

In the event that a new lm3533 is spawned from sysfs we would not have
platform_data when entering lm3533_device_init() and just bail early.

Therefor, this issue would be limited to the odd case of lm3533 being
initiated from code (e.g. a board file) on a DT enabled system. In which
case it will create and probe new devices from the root of the DT.

Regards,
Bjorn

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Thread

Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device  Tree Lee Jones <lee.jones@linaro.org> - 2017-01-04 13:10 +0100
  Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device  Tree Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-01-04 20:30 +0100
    Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device  Tree Lee Jones <lee.jones@linaro.org> - 2017-01-05 08:50 +0100
      Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device  Tree Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-01-05 17:40 +0100
        Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device  Tree Lee Jones <lee.jones@linaro.org> - 2017-01-06 11:00 +0100
          Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device  Tree Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-01-06 20:00 +0100
            Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device  Tree Lee Jones <lee.jones@linaro.org> - 2017-01-09 09:40 +0100
              Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device  Tree Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-01-11 21:00 +0100

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