linux-kernel - Re: [PATCH v2] dt: platform driver: Fill the resources before probe and defer if needed

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Message-Id: <20140317142443.A2447C40A85@trevor.secretlab.ca>
Date:	Mon, 17 Mar 2014 14:24:43 +0000
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Jean-Jacques Hiblot <jjhiblot@...phandler.com>
Cc:	devicetree <devicetree@...r.kernel.org>,
	Jean-Jacques Hiblot <jjhiblot@...phandler.com>,
	gregkh <gregkh@...uxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	robh+dt <robh+dt@...nel.org>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2] dt: platform driver: Fill the resources before probe and defer if needed

On Mon, 17 Mar 2014 12:07:37 +0100, Jean-Jacques Hiblot <jjhiblot@...phandler.com> wrote:
> Hi Grant,
> 
> Sorry for the delay, I was having nice vacations.
> 
> 2014-03-08 8:37 GMT+01:00 Grant Likely <grant.likely@...aro.org>:
> > On Fri, 21 Feb 2014 14:18:40 +0100, Jean-Jacques Hiblot <jjhiblot@...phandler.com> wrote:
> >> The goal of this patch is to allow drivers to be probed even if at the time of
> >> the DT parsing some of their ressources are not available yet.
> >
> > Hi Jean-Jacques
> >
> > [...]
> >> +int of_platform_device_prepare(struct platform_device *dev)
> >> +{
> >> +     struct device_node *np;
> >> +     int i, irq_index;
> >> +     struct resource *res;
> >> +
> >> +     /*
> >> +      * This function applies only devices described in the DT.
> >> +      * Other platform devices have their ressources already populated.
> >> +      */
> >> +     np = dev->dev.of_node;
> >> +     if (!np)
> >> +             return 0;
> >
> > I believe we already talked about the above test. This function must
> > only process devices created by of_platform_populate(). Merely checking
> > the of_node pointer is not a sufficient test because there are other
> > paths in the kernel for creating platform_devices that might get a node
> > pointer attached to it.
> Yes we talked about this, but only to move it into of_platform_device_prepare().
> Is there an existing way to know for sure that the device has been
> created by of_platform_populate() ? I could not find one.

No there isn't. That information is used at population time and then
discarded. We'd need to add a flag or registry to mark those devices.

g.

> 
> Jean-Jacques
> >
> > g.
> >
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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