Re: new cpu iteration code...

On Sun, Sep 22, 2013 at 3:29 PM, David Miller [off-list ref] wrote:

From: Rob Herring <redacted>
Date: Sun, 22 Sep 2013 15:13:35 -0500

quoted

On 09/20/2013 11:44 AM, Sudeep KarkadaNagesha wrote:

quoted

On 19/09/13 18:38, David Miller wrote:

quoted

From: Rob Herring <redacted>
Date: Thu, 19 Sep 2013 08:26:04 -0500

quoted

The simple solution here is to just remove the warning. It doesn't
appear to me that sparc ever sets the cpu device of_node pointer.

Why wouldn't I want sparc to have this functionality now that the
code is generically available.

Makes sense, but as you mentioned before we need to match other property
names namely "upa-portid", "portid" or "cpuid" for cpu physical id right
? Are all these 32-bit values ?

quoted

quoted

Are there any cases on where sparc does have a /cpus node? If so we'd
need to make of_get_cpu_node a weak function or depend on a kconfig option.

I already gave a solution to this problem, make the loop iterator be:

    for_each_node_by_type(dp, "cpu")

Does it make sense use this only when /cpus is not found ?
IMHO as the number of node in DT increases(which is the case on ARM
platforms) parsing entire tree may be expensive(which can be avoided in
case /cpus is found)

Can't you simply do something like this for the search:

      cpus = of_find_node_by_path("/cpus");
      if (!cpus && IS_ENABLED(CONFIG_SPARC))
              cpus = of_find_node_by_path("/");
      if (!cpus) {
              pr_warn("Missing cpus node, bailing out\n");
              return NULL;
      }

      for_each_child_of_node(cpus, cpun) {

This doesn't work either Rob.  Some UltraSPARC-IV systems put the cpu
nodes under directories representing the cores.

Okay. Good to know.

For the third time, the only thing which will work unilaterally is
the type base iterator I proposed above.

Now that I understand all the variations, I agree.

Why is there so much resistence to something which has an extremely
high likelyhood of working everywhere and not requiring any ifdef
crapola?

Simplifying Sudeep's code a bit while maintaining some level of
validation of the DT layout was my only goal. I guess that validation
really needs to be at build time rather than boot time and there is
some work going on in that area.

Rob
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