clk: clock multiplexers may register out of order

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>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: improve $SUBJECT]

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 2fd28ddd06c9..9955ad7e786e 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1298,12 +1298,20 @@ 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