[PATCH v2 1/2] clk: qcom: clk-rcg2: Update logic to calculate D value for RCG

[Taniya Das <tdas@codeaurora.org>]

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.

Fixes: 99cbd064b059f ("clk: qcom: Support display RCG clocks")
Signed-off-by: Taniya Das <tdas@codeaurora.org>
---
* Split the patch and update the Fixes tag.

 drivers/clk/qcom/clk-rcg2.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
index e1b1b426fae4..34251ec98def 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;
 	}
--
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