[PATCH v2 3/3] clk: nuvoton: ma35d1: fix ma35d1_clk_pll_determine_rate logic

[Joey Lu <a0987203069@gmail.com>]

ma35d1_clk_pll_determine_rate() called ma35d1_pll_find_closest()
unconditionally before the switch statement, and then every case
branch overwrote pll_freq by reading the current hardware registers.
For CAPLL and DDRPLL this means find_closest() ran unnecessarily
(and incorrectly, since those PLLs are read-only) and its result
was silently discarded.

Fix by moving the find_closest() call inside the APLL/EPLL/VPLL
branch where it belongs.  Group CAPLL and DDRPLL together as
read-only PLLs that simply report their current rate; handle them
with an explicit if/else to keep the CAPLL (SMIC design) and DDRPLL
(standard design) paths distinct.

Fixes: 691521a367cf ("clk: nuvoton: Add clock driver for ma35d1 clock controller")
Signed-off-by: Joey Lu <a0987203069@gmail.com>
---
 drivers/clk/nuvoton/clk-ma35d1-pll.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/clk/nuvoton/clk-ma35d1-pll.c b/drivers/clk/nuvoton/clk-ma35d1-pll.c
index 7e6b30d20c01..314b81e7727c 100644
--- a/drivers/clk/nuvoton/clk-ma35d1-pll.c
+++ b/drivers/clk/nuvoton/clk-ma35d1-pll.c
@@ -255,32 +255,32 @@ static int ma35d1_clk_pll_determine_rate(struct clk_hw *hw,
 	if (req->best_parent_rate < PLL_FREF_MIN_FREQ || req->best_parent_rate > PLL_FREF_MAX_FREQ)
 		return -EINVAL;
 
-	ret = ma35d1_pll_find_closest(pll, req->rate, req->best_parent_rate,
-				      reg_ctl, &pll_freq);
-	if (ret < 0)
-		return ret;
-
 	switch (pll->id) {
 	case CAPLL:
+	case DDRPLL:
+		/* Read-only PLLs: return current rate */
 		reg_ctl[0] = readl_relaxed(pll->ctl0_base);
-		pll_freq = ma35d1_calc_smic_pll_freq(reg_ctl[0], req->best_parent_rate);
+		if (pll->id == CAPLL) {
+			pll_freq = ma35d1_calc_smic_pll_freq(reg_ctl[0], req->best_parent_rate);
+		} else {
+			reg_ctl[1] = readl_relaxed(pll->ctl1_base);
+			pll_freq = ma35d1_calc_pll_freq(pll->mode, reg_ctl, req->best_parent_rate);
+		}
 		req->rate = pll_freq;
-
 		return 0;
-	case DDRPLL:
 	case APLL:
 	case EPLL:
 	case VPLL:
-		reg_ctl[0] = readl_relaxed(pll->ctl0_base);
-		reg_ctl[1] = readl_relaxed(pll->ctl1_base);
-		pll_freq = ma35d1_calc_pll_freq(pll->mode, reg_ctl, req->best_parent_rate);
+		/* Configurable PLLs: find closest achievable rate */
+		ret = ma35d1_pll_find_closest(pll, req->rate, req->best_parent_rate,
+					      reg_ctl, &pll_freq);
+		if (ret < 0)
+			return ret;
 		req->rate = pll_freq;
-
 		return 0;
 	}
 
 	req->rate = 0;
-
 	return 0;
 }
 
-- 
2.43.0