2023-07-17 14:21:44

by Frank Oltmanns

Subject: [PATCH v4 06/11] clk: sunxi-ng: Add helper function to find closest rate

The default behaviour of clocks in the sunxi-ng driver is to select a
clock rate that is closest to but less than the requested rate.

Add the ccu_is_better_rate() helper function that - depending on the
fact if thc CCU_FEATURE_CLOSEST_RATE flag is set - decides if a rate is
closer than another rate.

Signed-off-by: Frank Oltmanns <[email protected]>
---
drivers/clk/sunxi-ng/ccu_common.c | 12 ++++++++++++
drivers/clk/sunxi-ng/ccu_common.h | 5 +++++
2 files changed, 17 insertions(+)

diff --git a/drivers/clk/sunxi-ng/ccu_common.c b/drivers/clk/sunxi-ng/ccu_common.c
index 8d28a7a079d0..8babce55302f 100644
--- a/drivers/clk/sunxi-ng/ccu_common.c
+++ b/drivers/clk/sunxi-ng/ccu_common.c
@@ -39,6 +39,18 @@ void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
}
EXPORT_SYMBOL_NS_GPL(ccu_helper_wait_for_lock, SUNXI_CCU);

+bool ccu_is_better_rate(struct ccu_common *common,
+ unsigned long target_rate,
+ unsigned long current_rate,
+ unsigned long best_rate)
+{
+ if (common->features & CCU_FEATURE_CLOSEST_RATE)
+ return abs(current_rate - target_rate) < abs(best_rate - target_rate);
+
+ return current_rate <= target_rate && current_rate > best_rate;
+}
+EXPORT_SYMBOL_NS_GPL(ccu_is_better_rate, SUNXI_CCU);
+
/*
* This clock notifier is called when the frequency of a PLL clock is
* changed. In common PLL designs, changes to the dividers take effect
diff --git a/drivers/clk/sunxi-ng/ccu_common.h b/drivers/clk/sunxi-ng/ccu_common.h
index 5ad219f041d5..942a72c09437 100644
--- a/drivers/clk/sunxi-ng/ccu_common.h
+++ b/drivers/clk/sunxi-ng/ccu_common.h
@@ -53,6 +53,11 @@ struct sunxi_ccu_desc {

void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock);

+bool ccu_is_better_rate(struct ccu_common *common,
+ unsigned long target_rate,
+ unsigned long current_rate,
+ unsigned long best_rate);
+
struct ccu_pll_nb {
struct notifier_block clk_nb;
struct ccu_common *common;

--
2.41.0

2023-07-17 14:46:31

by Maxime Ripard

Subject: Re: [PATCH v4 06/11] clk: sunxi-ng: Add helper function to find closest rate

On Mon, 17 Jul 2023 15:34:30 +0200, Frank Oltmanns wrote:
> The default behaviour of clocks in the sunxi-ng driver is to select a
> clock rate that is closest to but less than the requested rate.
>
> Add the ccu_is_better_rate() helper function that - depending on the
> fact if thc CCU_FEATURE_CLOSEST_RATE flag is set - decides if a rate is
>
> [ ... ]

Acked-by: Maxime Ripard <[email protected]>

Thanks!
Maxime