linux-kernel - [PATCH v1] clk: qcom: clk-rcg2: Update logic to calculate D value for RCG

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Date:   Mon, 24 Jan 2022 22:44:15 +0530
From:   Taniya Das <tdas@...eaurora.org>
To:     Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette   <mturquette@...libre.com>
Cc:     linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Taniya Das <tdas@...eaurora.org>
Subject: [PATCH v1] clk: qcom: clk-rcg2: Update logic to calculate D value for RCG

The current implementation does not check for D value is within
the accepted range for a given M & N value. Update the logic to
calculate the final D value based on the range. While at it, add
support for 2/3 divider in frac_table_pixel.

Signed-off-by: Taniya Das <tdas@...eaurora.org>
---
 drivers/clk/qcom/clk-rcg2.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
index e1b1b426fae4..036c8071c07a 100644
--- a/drivers/clk/qcom/clk-rcg2.c
+++ b/drivers/clk/qcom/clk-rcg2.c
@@ -264,7 +264,7 @@ static int clk_rcg2_determine_floor_rate(struct clk_hw *hw,

 static int __clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
 {
-	u32 cfg, mask;
+	u32 cfg, mask, d_val, not2d_val;
 	struct clk_hw *hw = &rcg->clkr.hw;
 	int ret, index = qcom_find_src_index(hw, rcg->parent_map, f->src);

@@ -283,8 +283,18 @@ static int __clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
 		if (ret)
 			return ret;

+		/* Calculate 2d value */
+		d_val = f->n;
+
+		if (d_val > ((f->n - f->m) * 2))
+			d_val = (f->n - f->m) * 2;
+		else if (d_val < f->m)
+			d_val = f->m;
+
+		not2d_val = ~d_val & mask;
+
 		ret = regmap_update_bits(rcg->clkr.regmap,
-				RCG_D_OFFSET(rcg), mask, ~f->n);
+				RCG_D_OFFSET(rcg), mask, not2d_val);
 		if (ret)
 			return ret;
 	}
@@ -720,6 +730,7 @@ static const struct frac_entry frac_table_pixel[] = {
 	{ 2, 9 },
 	{ 4, 9 },
 	{ 1, 1 },
+	{ 2, 3 },
 	{ }
 };

--
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