8<---

@@ -584,7 +584,7 @@ EXPORT_SYMBOL_GPL(clk_get_rate);

?*/
?unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
?{
- ? ? ? unsigned long unused;
+ ? ? ? unsigned long parent_rate = 0;

? ? ? ?if (!clk)
? ? ? ? ? ? ? ?return -EINVAL;

@@ -592,10 +592,10 @@ unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)

? ? ? ?if (!clk->ops->round_rate)
? ? ? ? ? ? ? ?return clk->rate;

- ? ? ? if (clk->flags & CLK_SET_RATE_PARENT)
- ? ? ? ? ? ? ? return clk->ops->round_rate(clk->hw, rate, &unused);
- ? ? ? else
- ? ? ? ? ? ? ? return clk->ops->round_rate(clk->hw, rate, NULL);
+ ? ? ? if (clk->parent)
+ ? ? ? ? ? ? ? parent_rate = clk->parent->rate;
+
+ ? ? ? return clk->ops->round_rate(clk->hw, rate, &parent_rate);
?}

?/**

@@ -765,9 +765,12 @@ static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)

?static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
?{
? ? ? ?struct clk *top = clk;
- ? ? ? unsigned long best_parent_rate = clk->parent->rate;
+ ? ? ? unsigned long best_parent_rate = 0;
? ? ? ?unsigned long new_rate;

+ ? ? ? if (clk->parent)
+ ? ? ? ? ? ? ? best_parent_rate = clk->parent->rate;
+
? ? ? ?if (!clk->ops->round_rate && !(clk->flags & CLK_SET_RATE_PARENT)) {
? ? ? ? ? ? ? ?clk->new_rate = clk->rate;
? ? ? ? ? ? ? ?return NULL;

@@ -780,10 +783,7 @@ static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)

? ? ? ? ? ? ? ?goto out;
? ? ? ?}

- ? ? ? if (clk->flags & CLK_SET_RATE_PARENT)
- ? ? ? ? ? ? ? new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
- ? ? ? else
- ? ? ? ? ? ? ? new_rate = clk->ops->round_rate(clk->hw, rate, NULL);
+ ? ? ? new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);

? ? ? ?if (best_parent_rate != clk->parent->rate) {
? ? ? ? ? ? ? ?top = clk_calc_new_rates(clk->parent, best_parent_rate);

--->8

The reason behind the change is that any clk implements .round_rate will
mostly need to get the parent rate, no matter flag CLK_SET_RATE_PARENT
is set or not. ?Instead of expecting every .round_rate implementation
to get the parent rate in the way beloe

? ? ? ? parent_rate = __clk_get_rate(__clk_get_parent(hw->clk));

we can just pass the parent rate into .round_rate.

quoted

+ ? ? int ? ? ? ? ? ? (*set_parent)(struct clk_hw *hw, u8 index);
+ ? ? u8 ? ? ? ? ? ? ?(*get_parent)(struct clk_hw *hw);
+ ? ? int ? ? ? ? ? ? (*set_rate)(struct clk_hw *hw, unsigned long);

For the same reason, I would change .set_rate interface like below.

8<---

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index d5ac6a7..6bd8037 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c

@@ -119,7 +119,8 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,

?}
?EXPORT_SYMBOL_GPL(clk_divider_round_rate);

-static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate)
+static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? unsigned long parent_rate)
?{
? ? ? ?struct clk_divider *divider = to_clk_divider(hw);
? ? ? ?unsigned int div;

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index dbc310a..d74ac4b 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c

@@ -833,17 +833,18 @@ static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long even

?static void clk_change_rate(struct clk *clk)
?{
? ? ? ?struct clk *child;
- ? ? ? unsigned long old_rate;
+ ? ? ? unsigned long old_rate, parent_rate = 0;
? ? ? ?struct hlist_node *tmp;

? ? ? ?old_rate = clk->rate;
+ ? ? ? if (clk->parent)
+ ? ? ? ? ? ? ? parent_rate = clk->parent->rate;

? ? ? ?if (clk->ops->set_rate)
- ? ? ? ? ? ? ? clk->ops->set_rate(clk->hw, clk->new_rate);
+ ? ? ? ? ? ? ? clk->ops->set_rate(clk->hw, clk->new_rate, parent_rate);

? ? ? ?if (clk->ops->recalc_rate)
- ? ? ? ? ? ? ? clk->rate = clk->ops->recalc_rate(clk->hw,
- ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? clk->parent->rate);
+ ? ? ? ? ? ? ? clk->rate = clk->ops->recalc_rate(clk->hw, parent_rate);
? ? ? ?else
? ? ? ? ? ? ? ?clk->rate = clk->parent->rate;

diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 5508897..1031f1f 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h

@@ -125,7 +125,8 @@ struct clk_ops {

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?unsigned long *);
? ? ? ?int ? ? ? ? ? ? (*set_parent)(struct clk_hw *hw, u8 index);
? ? ? ?u8 ? ? ? ? ? ? ?(*get_parent)(struct clk_hw *hw);
- ? ? ? int ? ? ? ? ? ? (*set_rate)(struct clk_hw *hw, unsigned long);
+ ? ? ? int ? ? ? ? ? ? (*set_rate)(struct clk_hw *hw, unsigned long,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? unsigned long);
? ? ? ?void ? ? ? ? ? ?(*init)(struct clk_hw *hw);
?};

--->8

Then with parent rate passed into .round_rate and .set_rate like what
we do with .recalc_rate right now, we can save particular clk
implementation from calling __clk_get_parent() and __clk_get_rate to
get parent rate.

For example, the following will the be diff we gain on clk-divider.

8<---

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index 6bd8037..8a28ffb 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c

@@ -68,8 +68,8 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,

? ? ? ?if (divider->flags & CLK_DIVIDER_ONE_BASED)
? ? ? ? ? ? ? ?maxdiv--;

- ? ? ? if (!best_parent_rate) {
- ? ? ? ? ? ? ? parent_rate = __clk_get_rate(__clk_get_parent(hw->clk));
+ ? ? ? if (!(divider->flags & CLK_SET_RATE_PARENT)) {

+ ? ? ? ? ? ? ? parent_rate = *best_parent_rate;
? ? ? ? ? ? ? ?bestdiv = DIV_ROUND_UP(parent_rate, rate);
? ? ? ? ? ? ? ?bestdiv = bestdiv == 0 ? 1 : bestdiv;
? ? ? ? ? ? ? ?bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;

@@ -109,13 +109,7 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,

? ? ? ?int div;
? ? ? ?div = clk_divider_bestdiv(hw, rate, prate);

- ? ? ? if (prate)
- ? ? ? ? ? ? ? return *prate / div;
- ? ? ? else {
- ? ? ? ? ? ? ? unsigned long r;
- ? ? ? ? ? ? ? r = __clk_get_rate(__clk_get_parent(hw->clk));
- ? ? ? ? ? ? ? return r / div;
- ? ? ? }
+ ? ? ? return *prate / div;
?}
?EXPORT_SYMBOL_GPL(clk_divider_round_rate);

@@ -127,7 +121,7 @@ static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,

? ? ? ?unsigned long flags = 0;
? ? ? ?u32 val;

- ? ? ? div = __clk_get_rate(__clk_get_parent(hw->clk)) / rate;
+ ? ? ? div = parent_rate / rate;

? ? ? ?if (!(divider->flags & CLK_DIVIDER_ONE_BASED))
? ? ? ? ? ? ? ?div--;

--->8