This patch adds support for propagation of setup of clock's parent one level
up.
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
parent.
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 a004769..14eda80 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1595,6 +1595,12 @@ 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 == clk->num_parents) {
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 73bdb69..83c98d5 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -29,6 +29,7 @@
#define CLK_IS_BASIC BIT(5) /* Basic clk, can't do a to_clk_foo() */
#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_SET_PARENT_PARENT BIT(8) /* propagate parent change up one level */
struct clk_hw;
--
1.7.9.5
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