linux-kernel - [PATCH] clk: qcom: clk-alpha-pll: Do not use random stack value for recalc rate

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Message-ID: <20241127093623.80735-1-krzysztof.kozlowski@linaro.org>
Date: Wed, 27 Nov 2024 10:36:23 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Bjorn Andersson <andersson@...nel.org>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	linux-arm-msm@...r.kernel.org,
	linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: [PATCH] clk: qcom: clk-alpha-pll: Do not use random stack value for recalc rate

If regmap_read() fails, random stack value was used in calculating new
frequency in recalc_rate() callbacks.  Such failure is really not
expected as these are all MMIO reads, however code should be here
correct and bail out.  This also avoids possible warning on
uninitialized value.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
---
 drivers/clk/qcom/clk-alpha-pll.c | 41 ++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index 5e9217ea3760..0cd937ab47d0 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -682,9 +682,12 @@ clk_alpha_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
 	u32 alpha_width = pll_alpha_width(pll);
 
-	regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l);
+	if (regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l))
+		return 0;
+
+	if (regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &ctl))
+		return 0;
 
-	regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &ctl);
 	if (ctl & PLL_ALPHA_EN) {
 		regmap_read(pll->clkr.regmap, PLL_ALPHA_VAL(pll), &low);
 		if (alpha_width > 32) {
@@ -915,8 +918,11 @@ alpha_pll_huayra_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
 	u32 l, alpha = 0, ctl, alpha_m, alpha_n;
 
-	regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l);
-	regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &ctl);
+	if (regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l))
+		return 0;
+
+	if (regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &ctl))
+		return 0;
 
 	if (ctl & PLL_ALPHA_EN) {
 		regmap_read(pll->clkr.regmap, PLL_ALPHA_VAL(pll), &alpha);
@@ -1110,8 +1116,11 @@ clk_trion_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
 	u32 l, frac, alpha_width = pll_alpha_width(pll);
 
-	regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l);
-	regmap_read(pll->clkr.regmap, PLL_ALPHA_VAL(pll), &frac);
+	if (regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l))
+		return 0;
+
+	if (regmap_read(pll->clkr.regmap, PLL_ALPHA_VAL(pll), &frac))
+		return 0;
 
 	return alpha_pll_calc_rate(parent_rate, l, frac, alpha_width);
 }
@@ -1169,7 +1178,8 @@ clk_alpha_pll_postdiv_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 	struct clk_alpha_pll_postdiv *pll = to_clk_alpha_pll_postdiv(hw);
 	u32 ctl;
 
-	regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &ctl);
+	if (regmap_read(pll->clkr.regmap, PLL_USER_CTL(pll), &ctl))
+		return 0;
 
 	ctl >>= PLL_POST_DIV_SHIFT;
 	ctl &= PLL_POST_DIV_MASK(pll);
@@ -1385,8 +1395,11 @@ static unsigned long alpha_pll_fabia_recalc_rate(struct clk_hw *hw,
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
 	u32 l, frac, alpha_width = pll_alpha_width(pll);
 
-	regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l);
-	regmap_read(pll->clkr.regmap, PLL_FRAC(pll), &frac);
+	if (regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l))
+		return 0;
+
+	if (regmap_read(pll->clkr.regmap, PLL_FRAC(pll), &frac))
+		return 0;
 
 	return alpha_pll_calc_rate(parent_rate, l, frac, alpha_width);
 }
@@ -2457,9 +2470,12 @@ static unsigned long alpha_pll_lucid_evo_recalc_rate(struct clk_hw *hw,
 	struct regmap *regmap = pll->clkr.regmap;
 	u32 l, frac;
 
-	regmap_read(regmap, PLL_L_VAL(pll), &l);
+	if (regmap_read(regmap, PLL_L_VAL(pll), &l))
+		return 0;
 	l &= LUCID_EVO_PLL_L_VAL_MASK;
-	regmap_read(regmap, PLL_ALPHA_VAL(pll), &frac);
+
+	if (regmap_read(regmap, PLL_ALPHA_VAL(pll), &frac))
+		return 0;
 
 	return alpha_pll_calc_rate(parent_rate, l, frac, pll_alpha_width(pll));
 }
@@ -2534,7 +2550,8 @@ static unsigned long clk_rivian_evo_pll_recalc_rate(struct clk_hw *hw,
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
 	u32 l;
 
-	regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l);
+	if (regmap_read(pll->clkr.regmap, PLL_L_VAL(pll), &l))
+		return 0;
 
 	return parent_rate * l;
 }
-- 
2.43.0