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From: Grant Likely <grant.likely@secretlab.ca>
Date: Wed, 21 Nov 2012 18:07:46 +0000
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Subject: Re: [PATCH] of: Have of_device_add call platform_device_add rather
 than device_add
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rob Herring <rob.herring@calxeda.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        devicetree-discuss <devicetree-discuss@lists.ozlabs.org>
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On Wed, Nov 21, 2012 at 5:44 PM, Jason Gunthorpe
<jgunthorpe@obsidianresearch.com> wrote:
> On Wed, Nov 21, 2012 at 03:51:04PM +0000, Grant Likely wrote:
>> On Wed, 21 Nov 2012 00:24:48 -0700, Jason Gunthorpe <jgunthorpe@obsidianresearch.com> wrote:
>> > This allows platform_device_add a chance to call insert_resource
>> > on all of the resources from OF. At a minimum this fills in proc/iomem
>> > and presumably makes resource tracking and conflict detection work
>> > better.
>> >
>> > Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
>> >  drivers/of/device.c |    2 +-
>> >  1 files changed, 1 insertions(+), 1 deletions(-)
>> >
>> > Tested on PPC32 and ARM32 embedded kernels.
>> >
>> > diff --git a/drivers/of/device.c b/drivers/of/device.c
>> > index 4c74e4f..a5b67dc 100644
>> > +++ b/drivers/of/device.c
>> > @@ -62,7 +62,7 @@ int of_device_add(struct platform_device *ofdev)
>> >     if (!ofdev->dev.parent)
>> >             set_dev_node(&ofdev->dev, of_node_to_nid(ofdev->dev.of_node));
>> >
>> > -   return device_add(&ofdev->dev);
>> > +   return platform_device_add(ofdev);
>> >  }
>> >
>> >  int of_device_register(struct platform_device *pdev)
>>
>> This has the side effect of moving all devices at the root of the tree
>> from /sys/devices/ to /sys/devices/platform. It also has the possibility
>> of breaking if any devices get registered with overlapping regions. I
>> think there are some powerpc 5200 boards that do this, and I'm not sure
>> about the larger Power boxen.
>
> Okay, I'll try to test your patch.
>
> I know sensible overlapping seems to work:
>
> e0000000-e7ffffff : PCIe 0 MEM
>   e0000000-e000ffff : 0000:00:01.0
>     e0000000-e0000fff : /pex@e0000000/chip@0/chip_control@0
>       e0000008-e000000b : dat
>         e0000008-e000000b : dat
>       e000000c-e000000f : set
>         e000000c-e000000f : set
>       e0000010-e0000013 : dirin
>         e0000010-e0000013 : dirin
>
> Which is nesting the generic gpio driver under a larger region..

Try two sibling nodes with overlapping addresses. There are powerpc
device trees doing that even though it isn't legal by the ofw and
epapr specs.

g.