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

On Wed, Jun 08, 2016 at 11:46:41AM -0500, Rob Herring wrote:

On Wed, Jun 8, 2016 at 1:50 AM, Gavin Shan [off-list ref] wrote:

quoted

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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