Grant Likely [off-list ref] wrote @ Thu, 12 Dec 2013 12:34:17 +0100:

On Wed, 11 Dec 2013 14:33:38 +0100, Hiroshi Doyu [off-list ref] wrote:

quoted

Hi Grant,

Grant Likely [off-list ref] wrote @ Wed, 11 Dec 2013 14:28:45 +0100:

quoted

On Thu, 21 Nov 2013 11:57:00 -0700, Stephen Warren [off-list ref] wrote:

quoted

On 11/21/2013 10:17 AM, Hiroshi Doyu wrote:

quoted

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.

Signed-off-by: Hiroshi Doyu <redacted>
---
v6+:
Use the description, which Grant Likely proposed, to be full enough
that a future reader can figure out why a patch was written.
  http://lists.linuxfoundation.org/pipermail/iommu/2013-November/007062.html

...

quoted

That's right, I forgot I said that. Yes please fix the implementation.

Here's the latest. I'll include this with the next v7 series.

Can I get your Acked-by with this?

--8<----

From 8f7c0404aa68f0e8dbe0babc240590f6528ecc1f Mon Sep 17 00:00:00 2001
From: Hiroshi Doyu <redacted>
Date: Fri, 15 Nov 2013 10:52:53 +0200
Subject: [PATCH] of: introduce of_property_for_each_phandle_with_args()

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.

Signed-off-by: Hiroshi Doyu <redacted>
Cc: Rob Herring <redacted>
---
v7:
Fixed some minors pointed by Rob and Stephen.

v6++++:
Iterate without intrducing a new struct.

v6+++:
Introduced a new struct "of_phandle_iter" to keep the state when
iterating over the list.

v6++:
Optimized to avoid O(n^2), suggested by Stephen Warren.
http://lists.linuxfoundation.org/pipermail/iommu/2013-November/007066.html

I didn't introduce any struct to hold params and state here.

v6+:
Use the description, which Grant Likely proposed, to be full enough
that a future reader can figure out why a patch was written.

v5:
New patch for v5.

Signed-off-by: Hiroshi Doyu <redacted>
---
 drivers/of/base.c  | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of.h | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index f807d0e..cd4ab05 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c

@@ -1201,6 +1201,52 @@ void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
      printk("\n");
 }

+const __be32 *of_phandle_iter_next(const char *cells_name, int cell_count,
+                                const __be32 *cur, const __be32 *end,
+                                struct of_phandle_args *out_args)

Having to pass in cells_name, cell_count, cur and end each time seems a
little odd. Can a state structure be used instead?

struct of_phandle_iter_state {
        const char *cells_name;
        int cells_count;
        const __be32 *cur;
        const __be32 *end;
        struct of_phandle_args out_args;
}

Make the caller provide one of those and fill it in with the init
function.

I rewrote this a few times and so now I have a few version of this
implementations :-) The above proposal is similar to the version v6+++
mentioned in the above patch note:

quoted

v6+++:
Introduced a new struct "of_phandle_iter" to keep the state when
iterating over the list.

which is:

  [RFC][PATCHv6+++ 01/13] of: introduce of_property_for_earch_phandle_with_args()
    http://lists.linuxfoundation.org/pipermail/iommu/2013-November/007087.html

Stephen seemed to prefer the version without state struct. I like the
idea to not pass the same arguments repeatly. Instead, wrapping them
in a struct with state may look better.

So if Stephen agrees, I'll rewrite the version with state struct
again.