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

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Message-ID: <20231003062153.12215-3-jay.buddhabhatti@amd.com>
Date:   Mon, 2 Oct 2023 23:21:53 -0700
From:   Jay Buddhabhatti <jay.buddhabhatti@....com>
To:     <mturquette@...libre.com>, <sboyd@...nel.org>,
        <michal.simek@....com>
CC:     <linux-clk@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Jay Buddhabhatti <jay.buddhabhatti@....com>
Subject: [PATCH 2/2] drivers: clk: zynqmp: update divider round rate logic

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@....com>
---
 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