[PATCH 1/4] clk: propagate parent change up one level

From: Tomasz Stanislawski
Date: Fri Apr 04 2014 - 10:55:57 EST

This patch adds support for propagation of setup of clock's parent one level

This feature is helpful when a driver changes topology of its clocks using
clk_set_parent(). The problem occurs when on one platform/SoC driver's clock
is located at MUX output but on the other platform/SoC there is a gated proxy
clock between the MUX and driver's clock. In such a case, driver's code has to
be modified to use one clock for enabling and the other clock for setup of a

The code updates are avoided by propagating setup of a parent up one level.

Additionally, this patch adds CLK_SET_PARENT_PARENT (sorry for naming) flag to
inform clk-core that clk_set_parent() should be propagated.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
drivers/clk/clk.c | 6 ++++++
include/linux/clk-provider.h | 1 +
2 files changed, 7 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index dff0373..53bbfda 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1737,6 +1737,12 @@ int clk_set_parent(struct clk *clk, struct clk *parent)

/* try finding the new parent index */
if (parent) {
+ if ((clk->flags & CLK_SET_PARENT_PARENT)
+ && clk->num_parents == 1) {
+ ret = clk_set_parent(clk->parent, parent);
+ goto out;
+ }
p_index = clk_fetch_parent_index(clk, parent);
p_rate = parent->rate;
if (p_index < 0) {
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 5119174..daa0b03 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -30,6 +30,7 @@
#define CLK_GET_RATE_NOCACHE BIT(6) /* do not use the cached clk rate */
#define CLK_SET_RATE_NO_REPARENT BIT(7) /* don't re-parent on rate change */
#define CLK_GET_ACCURACY_NOCACHE BIT(8) /* do not use the cached clk accuracy */
+#define CLK_SET_PARENT_PARENT BIT(9) /* propagate parent change up one level */

struct clk_hw;
struct dentry;

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