[PATCH 1/2] clk: clk_resolve_parent_clk(): resolve external clocks by id

[chiffathefox]

When referencing clocks in DTS registered by another driver,
clk_resolve_parent_clk() is supposed to return the name
of the child device that provides the requested clock.
However, in reality, it returns the name of the parent DTB
node (e.g. clock-controller at 1a240000). Such devices, for
instance the exynos7870-cmu-peri driver, do not store any
clock information in their dev->uclass_priv_ because they
expect you to call dev->ops->get_rate with the appropriate
clk->id. So when you try to resolve a clock that depends on
an externally referenced clock, the resolution fails on the
parent clock because it doesn't have a  dev->uclass_priv_.
With this change clk_resolve_parent_clk() will take an
extra step to actually resolve the child device.

Signed-off-by: chiffathefox <chiffathefoxx at gmail.com>
---

 drivers/clk/clk-uclass.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c
index 0584429bed6..bea45fc396f 100644
--- a/drivers/clk/clk-uclass.c
+++ b/drivers/clk/clk-uclass.c
@@ -430,6 +430,7 @@ clk_resolve_parent_clk(struct udevice *dev, const char *name)
 {
 	struct udevice *parent;
 	struct clk clk;
+	struct clk *c;
 	int ret;
 
 	ret = uclass_get_device_by_name(UCLASS_CLK, name, &parent);
@@ -440,7 +441,11 @@ clk_resolve_parent_clk(struct udevice *dev, const char *name)
 	if (!clk.dev)
 		return name;
 
-	return clk.dev->name;
+	ret = clk_get_by_id(clk.id, &c);
+	if (ret)
+		return name;
+
+	return c->dev->name;
 }
 
 int clk_release_all(struct clk *clk, unsigned int count)
-- 
2.34.1