Re: [PATCH] drivers/of: Fix depth for sub-tree blob in unflatten_dt_nodes()

[Gavin Shan <gwshan-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

On Wed, Jun 08, 2016 at 11:46:41AM -0500, Rob Herring wrote:
>On Wed, Jun 8, 2016 at 1:50 AM, Gavin Shan <gwshan-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> wrote:
>> The function is unflattening device sub-tree blob if @dad passed to
>> the function is valid. Currently, this functionality is used by PPC
>> PowerNV PCI hotplug driver only. There are possibly multiple nodes
>> in the first level of depth, fdt_next_node() bails immediately when
>> @depth becomes negative before the second device node can be probed
>> successfully. It leads to the device nodes except the first one won't
>> be unflattened successfully.
>>
>> This fixes the issue by setting the initial depth (@inital_depth) to
>> 1 when this function is called to unflatten device sub-tree blob. No
>> logic changes when this function is used to unflatten non-sub-tree
>> blob.
>
>Does this affect anything besides your PCI hotplug stuff? I'd think
>overlays/changesets would be broken, but the unittests aren't failing
>that I recall.
>

Rob, it affects my PCI hotplug stuff only. There are two paths how
unflatten_dt_nodes() is called. No valid @dad specified in (A). PCI
hotplug is the only user specifying valid @dad in (B) and all other
users have invalid @dad.

          A                          B

   unflatten_device_tree     of_fdt_unflatten_tree
   __unflatten_device_tree   __unflatten_device_tree
   unflatten_dt_nodes        unflatten_dt_nodes

With or without this patch, I got same otuput from unittest as below:

### dt-test ### start of unittest - you will see error messages
/testcase-data/phandle-tests/consumer-a: could not get #phandle-cells-missing for /testcase-data/phandle-tests/provider1
/testcase-data/phandle-tests/consumer-a: could not get #phandle-cells-missing for /testcase-data/phandle-tests/provider1
/testcase-data/phandle-tests/consumer-a: could not find phandle
/testcase-data/phandle-tests/consumer-a: could not find phandle
/testcase-data/phandle-tests/consumer-a: arguments longer than property
/testcase-data/phandle-tests/consumer-a: arguments longer than property
irq: XICS didn't like hwirq-0x1 to VIRQ27 mapping (rc=-22)
irq: XICS didn't like hwirq-0x1 to VIRQ27 mapping (rc=-22)
### dt-test ### FAIL of_unittest_platform_populate():782 device deferred probe failed - 0
overlay_is_topmost: #5 clashes #6 @/testcase-data/overlay-node/test-bus/test-unittest8
overlay_removal_is_ok: overlay #5 is not topmost
of_overlay_destroy: removal check failed for overlay #5
### dt-test ### end of unittest - 147 passed, 1 failed


>Rob
>

Thanks,
Gavin

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