Re: [PATCHv5 1/9] of: introduce of_property_for_earch_phandle_with_args()

From: Grant Likely
Date: Thu Nov 21 2013 - 10:56:59 EST


On Thu, 21 Nov 2013 15:12:18 +0200, Hiroshi Doyu <hdoyu@xxxxxxxxxx> wrote:
> On Thu, 21 Nov 2013 13:43:28 +0100
> Grant Likely <grant.likely@xxxxxxxxxx> wrote:
>
> > On Tue, 19 Nov 2013 11:33:05 +0200, Hiroshi Doyu <hdoyu@xxxxxxxxxx> wrote:
> > > The following pattern of code is tempting:
> > >
> > > for (i = 0; !of_parse_phandle_with_args(np, list, cells, i, args); i++)
> > >
> > > Signed-off-by: Hiroshi Doyu <hdoyu@xxxxxxxxxx>
> >
> > That's a very minimal commit message. Can you elaborate please.
>
> The above can be:
>
> "
> The following pattern of code is tempting to add a new member for
> of_property_for_each_*() family as an idiom.
>
> for (i = 0;
> !of_parse_phandle_with_args(np, list, cells, i, args); i++)
> <do something with "args">;
> "

I really do like commit messages to be full enough that a future reader
can figure out why a patch was written. ie:

"Iterating over a property containing a list of phandles with
arguments is a common operation for device drivers. This patch
adds a new of_property_for_each_phandle_with_args() macro to
make the iteration simpler."

g.

>
> Actual usage is here:
>
> int i;
> struct of_phandle_args args;
>
> of_property_for_each_phandle_with_args(dev->of_node, "iommus",
> "#iommu-cells", i, &args) {
> pr_debug("%s(i=%d) %s\n", __func__, i, dev_name(dev));
>
> if (!of_find_iommu_by_node(args.np))
> return -EPROBE_DEFER;
>
> Is this acceptable?

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