[PATCH] ARM : CLK: Fix clock multiplexers when registered before their parents.

[PATCH] ARM : CLK: Fix clock multiplexers when registered before their parents.

[Martin Fuzzey]

When a clock, C is initialised any orphan clocks listing C as
a possible parent are reparented to it regardless of the
parent requested by the orphan's get_parent() operation.

This means that multiplexers registered before their parents
are reparented to the first parent subsequently declared,
regardless of the selection made by the hardware registers.

For example:
	static const char *sel[] = { "srcA", "srcB", "dummy", "srcC" };

	child = clk_register_mux(NULL, "child",  sel, ARRAY_SIZE(sel), ...);
	clk_register_fixed(NULL, "dummy", ...);
	clk_register_fixed(NULL, "srcA", ...);
	clk_register_fixed(NULL, "srcB", ...);
	clk_register_fixed(NULL, "srcC", ...);

Causes child's parent to always be "dummy".

To fix this, when an orphanned clock has a get_parent() operation,
only reparent to the clock indicated by get_parent().

Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
---
 drivers/clk/clk.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index aae7b99..4c605ea 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1307,12 +1307,20 @@ int __clk_init(struct device *dev, struct clk *clk)
 	 * walk the list of orphan clocks and reparent any that are children of
 	 * this clock
 	 */
-	hlist_for_each_entry_safe(orphan, tmp, tmp2, &clk_orphan_list, child_node)
+	hlist_for_each_entry_safe(orphan, tmp, tmp2, &clk_orphan_list, child_node) {
+		if (orphan->ops->get_parent) {
+			i = orphan->ops->get_parent(orphan->hw);
+			if (!strcmp(clk->name, orphan->parent_names[i]))
+				__clk_reparent(orphan, clk);
+			continue;
+		}
+
 		for (i = 0; i < orphan->num_parents; i++)
 			if (!strcmp(clk->name, orphan->parent_names[i])) {
 				__clk_reparent(orphan, clk);
 				break;
 			}
+	 }
 
 	/*
 	 * optional platform-specific magic

[PATCH] ARM : CLK: Fix clock multiplexers when registered before their parents.

[Mike Turquette]

Quoting Martin Fuzzey (2012-11-22 11:15:05)
> When a clock, C is initialised any orphan clocks listing C as
> a possible parent are reparented to it regardless of the
> parent requested by the orphan's get_parent() operation.
> 
> This means that multiplexers registered before their parents
> are reparented to the first parent subsequently declared,
> regardless of the selection made by the hardware registers.
> 
> For example:
>         static const char *sel[] = { "srcA", "srcB", "dummy", "srcC" };
> 
>         child = clk_register_mux(NULL, "child",  sel, ARRAY_SIZE(sel), ...);
>         clk_register_fixed(NULL, "dummy", ...);
>         clk_register_fixed(NULL, "srcA", ...);
>         clk_register_fixed(NULL, "srcB", ...);
>         clk_register_fixed(NULL, "srcC", ...);
> 
> Causes child's parent to always be "dummy".
> 
> To fix this, when an orphanned clock has a get_parent() operation,
> only reparent to the clock indicated by get_parent().
> 
> Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>

Thank you for the fix Martin.  This one got lost in the "todo" pile a
long time ago since most platforms register their clocks in-order from
root nodes to leaf nodes.

Applied to clk-next.

Regards,
Mike

> ---
>  drivers/clk/clk.c |   10 +++++++++-
>  1 files changed, 9 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index aae7b99..4c605ea 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1307,12 +1307,20 @@ int __clk_init(struct device *dev, struct clk *clk)
>          * walk the list of orphan clocks and reparent any that are children of
>          * this clock
>          */
> -       hlist_for_each_entry_safe(orphan, tmp, tmp2, &clk_orphan_list, child_node)
> +       hlist_for_each_entry_safe(orphan, tmp, tmp2, &clk_orphan_list, child_node) {
> +               if (orphan->ops->get_parent) {
> +                       i = orphan->ops->get_parent(orphan->hw);
> +                       if (!strcmp(clk->name, orphan->parent_names[i]))
> +                               __clk_reparent(orphan, clk);
> +                       continue;
> +               }
> +
>                 for (i = 0; i < orphan->num_parents; i++)
>                         if (!strcmp(clk->name, orphan->parent_names[i])) {
>                                 __clk_reparent(orphan, clk);
>                                 break;
>                         }
> +        }
>  
>         /*
>          * optional platform-specific magic