linux-kernel - Re: [PATCH] TESTCASE: of: OOPS when disabling node via OF

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Message-Id: <20150610165322.576FDC408EA@trevor.secretlab.ca>
Date:	Wed, 10 Jun 2015 17:53:22 +0100
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:	Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
	Wolfram Sang <wsa@...-dreams.de>, devicetree@...r.kernel.org,
	linux-sh@...r.kernel.org, Magnus Damm <magnus.damm@...il.com>,
	Simon Horman <horms@...ge.net.au>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Rob Herring <robh+dt@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] TESTCASE: of: OOPS when disabling node via OF_DYNAMIC

On Tue, 09 Jun 2015 19:50:26 +0300
, Laurent Pinchart <laurent.pinchart@...asonboard.com>
 wrote:
> Hi Grant,
> 
> On Sunday 07 June 2015 12:16:32 Grant Likely wrote:
> > On Wed, 22 Apr 2015 15:30:28 +0300, Pantelis Antoniou wrote:
> > > > On Apr 14, 2015, at 16:27 , Wolfram Sang <wsa@...-dreams.de> wrote:
> > > > 
> > > > Hi Pantelis,
> > > > 
> > > > thanks for your prompt reply. Unfortunately, I had to wait until I could
> > > > access the test system again.
> > > 
> > > [snip]
> > > 
> > > Sorry for the non-prompt reply; but just for kicks, can you try the
> > > attached patch?
> > > 
> > > I have a hunch this might be the problem.
> > > 
> > > Regards
> > > 
> > > â Pantelis
> > 
> > I played around with this some today. If I'm reading it correctly, the
> > following patch reproduces the same problem:
> > 
> > (continued below patch)
> > ---
> > diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
> > index 18016341d5a9..0a27b38c3041 100644
> > --- a/drivers/of/unittest.c
> > +++ b/drivers/of/unittest.c
> > @@ -753,6 +753,11 @@ static void __init of_unittest_match_node(void)
> >  	}
> >  }
> > 
> > +static struct resource test_bus_res = {
> > +	.start = 0xfffffff8,
> > +	.end = 0xfffffff9,
> > +	.flags = IORESOURCE_MEM,
> > +};
> >  static const struct platform_device_info test_bus_info = {
> >  	.name = "unittest-bus",
> >  };
> > @@ -795,6 +800,7 @@ static void __init of_unittest_platform_populate(void)
> >  	if (rc)
> >  		return;
> >  	test_bus->dev.of_node = np;
> > +	platform_device_add_resources(test_bus, &test_bus_res, 1);
> > 
> >  	of_platform_populate(np, match, NULL, &test_bus->dev);
> >  	for_each_child_of_node(np, child) {
> > 
> > ---
> > 
> > I think the fixup patch boils down to the following. It's hard to tell
> > because it combines refactoring with the bug fix. Do I have it correct?
> > If so, I'd rather commit the simple fix which can be committed now for
> > v4.1, and the refactoring can be pushed for v4.2
> 
> The patch below looks equivalent to Pantelis' patch if we remove the 
> refactoring, but I don't immediately see how r->parent can be NULL in 
> platform_device_del() if type is equal to IORESOURCE_MEM or IORESOURCE_IO, as 
> platform_device_add() will have called insert_resource() in those cases, which 
> should set the resource parent pointer. I must be missing something as the 
> patch fixes Wolfram's issue, so an explanation in the commit message would be 
> welcome.

of_platform_populate() adds platform devices via of_device_add().
of_device_add() doesn't add the resources because there are platforms
that break due to nodes with overlapping resources.

g.
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