Re: [PATCH V3 5/6] Avoid duplicate probe for of platform devices

On 07/08/2012 10:46 PM, Li Yang-R58472 wrote:

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I don't understand, why is this just showing up now?  What
changed to cause this?  Couldn't that be the real problem here?

The issue is showing up because we now probe devices twice. 
Previously, we just probe devices once. But now we changed the way
of pci init which makes pci controllers should be probed earlier
than other devices. So we have to probe pci nodes separately. Probe
more than once is the root cause of this issue.

The pci patchset I mentioned please refer to: 
http://patchwork.ozlabs.org/patch/163742/

Let me try to clarify a little bit.  The of platform bus normally
traverse the device tree to add all the devices.  The change which
caused problem is that we need to probe PCIe RC devices at a earlier
stage of initialization.  So we added these PCIe RC devices earlier
than the normal device tree traversal process.  These PCIe RC devices
will be scanned again during the normal traversal and cause
duplicated devices being added.  Our proposal is to deal with
duplicated devices automatically and make it possible to scan the
device tree multiple times for devices to be added.

What is making PCI need to be probed earlier? Perhaps deferred probe
would work?

Perhaps giving of_platform_populate an exclude list of compatible
strings to skip would work.

Rob