OF_DYNAMIC node lifecycle

Grant Likely grant.likely at linaro.org
Thu Jul 17 10:44:09 EST 2014

On Wed, Jul 16, 2014 at 5:12 PM, Nathan Fontenot <nfont at austin.ibm.com> wrote:
> On 07/16/2014 05:26 PM, Grant Likely wrote:
>> On Wed, Jul 16, 2014 at 2:57 PM, Grant Likely <grant.likely at linaro.org> wrote:
>>> On Wed, Jul 16, 2014 at 12:30 PM, Tyrel Datwyler
>>> <turtle.in.the.kernel at gmail.com> wrote:
>>>> On 07/15/2014 10:33 PM, Grant Likely wrote:
>>>>> I've got another question about powerpc reconfiguration. I was looking
>>>>> at the dlpar_configure_connector() function in dlpar.c. I see that the
>>>>> function has the ability to process multiple nodes with additional
>>>>> sibling and child nodes. It appears to link them into a detached tree
>>>>> structure, and the function returns a pointer to the first node.
>>>>> All of the callers of that function then call dlpar_attach_node(),
>>>>> which calls of_attach_node(). However, of_attach_node() only handles a
>>>>> single node. It doesn't handle siblings or children. Is this a bug?
>>>>> Does the configure connector ever actually receive more than one node
>>>>> at once?
>>>> Yes, it is sometimes the case we will get a tree structure back of more
>>>> than one node. Under the proc interface implementation this just worked.
>>>> With the move to sysfs it appears we have a regression here. What makes
>>>> more sense here, for us to walk the tree calling of_attach_node, or to
>>>> move such tree walking logic into of_attach_node? From what I can tell
>>>> we are the only consumers of of_attach_node.
>>> That is very shortly going to change. The overlay code also uses
>>> of_attach_node(). I can make of_attach_node() recurse over
>>> descendants, but I'm also considering moving the powerpc code over to
>>> the of_changeset series that Panto and I are working on.
>>> Either way, the handling of multiple nodes should be common code. I
>>> think the easiest is to put the recursion into of_attach_node(), at
>>> least for fixing the bug. It can be reworked later.
>> On pseries, do notifiers ever fail? ie. Does the reconfig code ever
>> object to a DT change and prevent it from being applied?
> I cannot think of a time that  I ever saw a notifier fail.

Good to know. I was hoping it wasn't part of the design. I can't think
of any situation where the kernel would want to inhibit a change to
the device tree.

Can you take a look at the following tree and give it a spin on
PowerPC. I've reordered the notifiers and hopefully got the powerpc
fixups right, but I don't have a way to test it...

The following changes since commit cd3de83f147601356395b57a8673e9c5ff1e59d1:

  Linux 3.16-rc4 (2014-07-06 12:37:51 -0700)

are available in the git repository at:

  git://git.secretlab.ca/git/linux devicetree/next-overlay

for you to fetch changes up to 44ac93bb5583c5f1f85912309fe04045b61a6dd0:

  of: Transactional DT support. (2014-07-16 16:44:07 -0600)

Grant Likely (6):
      of/platform: Fix of_platform_device_destroy iteration of devices
      of: Move CONFIG_OF_DYNAMIC code into a separate file
      of: Make sure attached nodes don't carry along extra children
      of: Move dynamic node fixups out of powerpc and into common code
      of: Make OF_DYNAMIC user selectable
      of: Reorder device tree changes and notifiers

Pantelis Antoniou (5):
      of: rename of_aliases_mutex to just of_mutex
      OF: Utility helper functions for dynamic nodes
      of: Create unlocked versions of node and property add/remove functions
      of: Make devicetree sysfs update functions consistent.
      of: Transactional DT support.

 Documentation/devicetree/changesets.txt         |  41 ++
 arch/powerpc/kernel/prom.c                      |  70 ---
 arch/powerpc/platforms/pseries/hotplug-memory.c |   2 +-
 drivers/crypto/nx/nx-842.c                      |  30 +-
 drivers/of/Kconfig                              |   2 +-
 drivers/of/Makefile                             |   1 +
 drivers/of/base.c                               | 423 ++++-----------
 drivers/of/device.c                             |   4 +-
 drivers/of/dynamic.c                            | 671 ++++++++++++++++++++++++
 drivers/of/of_private.h                         |  59 ++-
 drivers/of/platform.c                           |  32 +-
 drivers/of/selftest.c                           |  79 +++
 drivers/of/testcase-data/testcases.dtsi         |  10 +
 include/linux/of.h                              |  80 ++-
 include/linux/of_platform.h                     |   7 +-
 15 files changed, 1067 insertions(+), 444 deletions(-)
 create mode 100644 Documentation/devicetree/changesets.txt
 create mode 100644 drivers/of/dynamic.c

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