[PATCH 2/2] drivers: clk: zynqmp: update divider round rate logic

From: Jay Buddhabhatti
Date: Tue Oct 03 2023 - 02:22:49 EST


Currently zynqmp divider round rate is considering single parent and
calculating rate and parent rate accordingly. But if divider clock flag
is set to SET_RATE_PARENT then its not trying to traverse through all
parent rate and not selecting best parent rate from that. So use common
divider_round_rate() which is traversing through all clock parents and
its rate and calculating proper parent rate.

Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@xxxxxxx>
---
drivers/clk/zynqmp/divider.c | 70 ++++++------------------------------
1 file changed, 10 insertions(+), 60 deletions(-)

diff --git a/drivers/clk/zynqmp/divider.c b/drivers/clk/zynqmp/divider.c
index 33a3b2a22659..a42c183d7e5d 100644
--- a/drivers/clk/zynqmp/divider.c
+++ b/drivers/clk/zynqmp/divider.c
@@ -110,52 +110,6 @@ static unsigned long zynqmp_clk_divider_recalc_rate(struct clk_hw *hw,
return DIV_ROUND_UP_ULL(parent_rate, value);
}

-static void zynqmp_get_divider2_val(struct clk_hw *hw,
- unsigned long rate,
- struct zynqmp_clk_divider *divider,
- u32 *bestdiv)
-{
- int div1;
- int div2;
- long error = LONG_MAX;
- unsigned long div1_prate;
- struct clk_hw *div1_parent_hw;
- struct zynqmp_clk_divider *pdivider;
- struct clk_hw *div2_parent_hw = clk_hw_get_parent(hw);
-
- if (!div2_parent_hw)
- return;
-
- pdivider = to_zynqmp_clk_divider(div2_parent_hw);
- if (!pdivider)
- return;
-
- div1_parent_hw = clk_hw_get_parent(div2_parent_hw);
- if (!div1_parent_hw)
- return;
-
- div1_prate = clk_hw_get_rate(div1_parent_hw);
- *bestdiv = 1;
- for (div1 = 1; div1 <= pdivider->max_div;) {
- for (div2 = 1; div2 <= divider->max_div;) {
- long new_error = ((div1_prate / div1) / div2) - rate;
-
- if (abs(new_error) < abs(error)) {
- *bestdiv = div2;
- error = new_error;
- }
- if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
- div2 = div2 << 1;
- else
- div2++;
- }
- if (pdivider->flags & CLK_DIVIDER_POWER_OF_TWO)
- div1 = div1 << 1;
- else
- div1++;
- }
-}
-
/**
* zynqmp_clk_divider_round_rate() - Round rate of divider clock
* @hw: handle between common and hardware-specific interfaces
@@ -174,6 +128,8 @@ static long zynqmp_clk_divider_round_rate(struct clk_hw *hw,
u32 div_type = divider->div_type;
u32 bestdiv;
int ret;
+ u8 width = 0;
+ u16 max;

/* if read only, just return current value */
if (divider->flags & CLK_DIVIDER_READ_ONLY) {
@@ -193,23 +149,17 @@ static long zynqmp_clk_divider_round_rate(struct clk_hw *hw,
return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
}

- bestdiv = zynqmp_divider_get_val(*prate, rate, divider->flags);
-
- /*
- * In case of two divisors, compute best divider values and return
- * divider2 value based on compute value. div1 will be automatically
- * set to optimum based on required total divider value.
- */
- if (div_type == TYPE_DIV2 &&
- (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
- zynqmp_get_divider2_val(hw, rate, divider, &bestdiv);
+ max = divider->max_div;
+ while (max != 0) {
+ if ((max & 1) == 1)
+ width++;
+ max = max >> 1;
}

- if ((clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) && divider->is_frac)
- bestdiv = rate % *prate ? 1 : bestdiv;
+ rate = divider_round_rate(hw, rate, prate, NULL, width, divider->flags);

- bestdiv = min_t(u32, bestdiv, divider->max_div);
- *prate = rate * bestdiv;
+ if (divider->is_frac && (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) && (rate % *prate))
+ *prate = rate;

return rate;
}
--
2.17.1