From: Benjamin Bara <[email protected]>
This function can be used to set the rate of a clock hardware from a
driver, e.g. to adapt the rate to a clock change coming from the parent.
Signed-off-by: Benjamin Bara <[email protected]>
---
drivers/clk/clk.c | 15 +++++++++++++++
include/linux/clk-provider.h | 1 +
2 files changed, 16 insertions(+)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index c249f9791ae8..3e222802b712 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2462,6 +2462,21 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
return ret;
}
+int clk_hw_set_rate(struct clk_hw *hw, unsigned long req_rate)
+{
+ /* A rate change is ongoing, so just target the required rate.
+ * Note: this does not work if one clock along the line has
+ * CLK_RECALC_NEW_RATES active, as this overwrites the new_rate again.
+ */
+ if (hw->core->new_rate != hw->core->rate) {
+ hw->core->new_rate = req_rate;
+ return 0;
+ }
+
+ return clk_core_set_rate_nolock(hw->core, req_rate);
+}
+EXPORT_SYMBOL_GPL(clk_hw_set_rate);
+
/**
* clk_set_rate - specify a new rate for clk
* @clk: the clk whose rate is being changed
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index ec32ec58c59f..3fb99ed5e8d9 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -1316,6 +1316,7 @@ int clk_hw_get_parent_index(struct clk_hw *hw);
int clk_hw_set_parent(struct clk_hw *hw, struct clk_hw *new_parent);
unsigned int __clk_get_enable_count(struct clk *clk);
unsigned long clk_hw_get_rate(const struct clk_hw *hw);
+int clk_hw_set_rate(struct clk_hw *hw, unsigned long req_rate);
unsigned long clk_hw_get_flags(const struct clk_hw *hw);
#define clk_hw_can_set_rate_parent(hw) \
(clk_hw_get_flags((hw)) & CLK_SET_RATE_PARENT)
--
2.34.1
Hi,
On Mon, Sep 18, 2023 at 12:39:59AM +0200, Benjamin Bara wrote:
> From: Benjamin Bara <[email protected]>
>
> This function can be used to set the rate of a clock hardware from a
> driver, e.g. to adapt the rate to a clock change coming from the parent.
>
> Signed-off-by: Benjamin Bara <[email protected]>
> ---
> drivers/clk/clk.c | 15 +++++++++++++++
> include/linux/clk-provider.h | 1 +
> 2 files changed, 16 insertions(+)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index c249f9791ae8..3e222802b712 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -2462,6 +2462,21 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
> return ret;
> }
>
> +int clk_hw_set_rate(struct clk_hw *hw, unsigned long req_rate)
> +{
> + /* A rate change is ongoing, so just target the required rate.
> + * Note: this does not work if one clock along the line has
> + * CLK_RECALC_NEW_RATES active, as this overwrites the new_rate again.
> + */
> + if (hw->core->new_rate != hw->core->rate) {
> + hw->core->new_rate = req_rate;
> + return 0;
> + }
> +
> + return clk_core_set_rate_nolock(hw->core, req_rate);
> +}
> +EXPORT_SYMBOL_GPL(clk_hw_set_rate);
So, we discussed it recently, and it's non-obvious to see how it would
work if you're in a set_rate change that modifies the tree and the new
call to clk_hw_set_rate modifies the tree too. Some explanation on how
it's handled, and some unit tests are required here imo.
Maxime