diff mbox series

[v2] phy: stm32: Optimize tuning values from DT.

Message ID 20250113092001.1344151-1-christian.bruel@foss.st.com
State New
Headers show
Series [v2] phy: stm32: Optimize tuning values from DT. | expand

Commit Message

Christian Bruel Jan. 13, 2025, 9:20 a.m. UTC 
phy_init can be recalled during PM resume. Thus cache the tuning values
read from the device tree.
Don't read the known default ohm value from regmap.

Signed-off-by: Christian Bruel <christian.bruel@foss.st.com>
---
v2: Fix 'val' uninitialized variable from clang build bot

 drivers/phy/st/phy-stm32-combophy.c | 84 ++++++++++++++---------------
 1 file changed, 42 insertions(+), 42 deletions(-)

Comments

Dan Carpenter Jan. 17, 2025, 8:38 a.m. UTC | #1 
Hi Christian,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Christian-Bruel/phy-stm32-Optimize-tuning-values-from-DT/20250113-172435
base:   v6.13-rc7
patch link:    https://lore.kernel.org/r/20250113092001.1344151-1-christian.bruel%40foss.st.com
patch subject: [PATCH v2] phy: stm32: Optimize tuning values from DT.
config: arm-randconfig-r071-20250117 (https://download.01.org/0day-ci/archive/20250117/202501171619.0XDYDyBZ-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 14.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202501171619.0XDYDyBZ-lkp@intel.com/

New smatch warnings:
drivers/phy/st/phy-stm32-combophy.c:147 stm32_impedance_tune() error: buffer overflow 'imp_lookup' 8 <= 8 (assuming for loop doesn't break)
drivers/phy/st/phy-stm32-combophy.c:564 stm32_combophy_probe() warn: passing zero to 'dev_err_probe'

vim +147 drivers/phy/st/phy-stm32-combophy.c

31219ca5436f01 Christian Bruel 2025-01-13  119  static void stm32_impedance_tune(struct stm32_combophy *combophy)
47e1bb6b4ba098 Christian Bruel 2024-09-30  120  {
47e1bb6b4ba098 Christian Bruel 2024-09-30  121  	u8 imp_of, vswing_of;
2de679ecd724b8 Arnd Bergmann   2024-11-11  122  	u32 regval;
47e1bb6b4ba098 Christian Bruel 2024-09-30  123  
31219ca5436f01 Christian Bruel 2025-01-13  124  	if (combophy->microohm) {
2de679ecd724b8 Arnd Bergmann   2024-11-11  125  		regval = 0;
2de679ecd724b8 Arnd Bergmann   2024-11-11  126  		for (imp_of = 0; imp_of < ARRAY_SIZE(imp_lookup); imp_of++) {
31219ca5436f01 Christian Bruel 2025-01-13  127  			if (imp_lookup[imp_of].microohm <= combophy->microohm) {
2de679ecd724b8 Arnd Bergmann   2024-11-11  128  				regval = FIELD_PREP(STM32MP25_PCIEPRG_IMPCTRL_OHM, imp_of);
47e1bb6b4ba098 Christian Bruel 2024-09-30  129  				break;
2de679ecd724b8 Arnd Bergmann   2024-11-11  130  			}
2de679ecd724b8 Arnd Bergmann   2024-11-11  131  		}

If we don't hit the break sttaement above

47e1bb6b4ba098 Christian Bruel 2024-09-30  132  
47e1bb6b4ba098 Christian Bruel 2024-09-30  133  		dev_dbg(combophy->dev, "Set %u micro-ohms output impedance\n",
47e1bb6b4ba098 Christian Bruel 2024-09-30  134  			imp_lookup[imp_of].microohm);
                                                                                   ^^^^^^
Then this is an out of bounds access.

47e1bb6b4ba098 Christian Bruel 2024-09-30  135  
47e1bb6b4ba098 Christian Bruel 2024-09-30  136  		regmap_update_bits(combophy->regmap, SYSCFG_PCIEPRGCR,
47e1bb6b4ba098 Christian Bruel 2024-09-30  137  				   STM32MP25_PCIEPRG_IMPCTRL_OHM,
2de679ecd724b8 Arnd Bergmann   2024-11-11  138  				   regval);
47e1bb6b4ba098 Christian Bruel 2024-09-30  139  	} else {
31219ca5436f01 Christian Bruel 2025-01-13  140  		/* default is 50 ohm */
31219ca5436f01 Christian Bruel 2025-01-13  141  		imp_of = 3;
47e1bb6b4ba098 Christian Bruel 2024-09-30  142  	}
47e1bb6b4ba098 Christian Bruel 2024-09-30  143  
31219ca5436f01 Christian Bruel 2025-01-13  144  	if (combophy->microvolt) {
2de679ecd724b8 Arnd Bergmann   2024-11-11  145  		regval = 0;
2de679ecd724b8 Arnd Bergmann   2024-11-11  146  		for (vswing_of = 0; vswing_of < ARRAY_SIZE(imp_lookup[imp_of].vswing); vswing_of++) {
31219ca5436f01 Christian Bruel 2025-01-13 @147  			if (imp_lookup[imp_of].vswing[vswing_of] >= combophy->microvolt) {
2de679ecd724b8 Arnd Bergmann   2024-11-11  148  				regval = FIELD_PREP(STM32MP25_PCIEPRG_IMPCTRL_VSWING, vswing_of);
47e1bb6b4ba098 Christian Bruel 2024-09-30  149  				break;
2de679ecd724b8 Arnd Bergmann   2024-11-11  150  			}
2de679ecd724b8 Arnd Bergmann   2024-11-11  151  		}
47e1bb6b4ba098 Christian Bruel 2024-09-30  152  
47e1bb6b4ba098 Christian Bruel 2024-09-30  153  		dev_dbg(combophy->dev, "Set %u microvolt swing\n",
47e1bb6b4ba098 Christian Bruel 2024-09-30  154  			 imp_lookup[imp_of].vswing[vswing_of]);
47e1bb6b4ba098 Christian Bruel 2024-09-30  155  
47e1bb6b4ba098 Christian Bruel 2024-09-30  156  		regmap_update_bits(combophy->regmap, SYSCFG_PCIEPRGCR,
47e1bb6b4ba098 Christian Bruel 2024-09-30  157  				   STM32MP25_PCIEPRG_IMPCTRL_VSWING,
2de679ecd724b8 Arnd Bergmann   2024-11-11  158  				   regval);
47e1bb6b4ba098 Christian Bruel 2024-09-30  159  	}
47e1bb6b4ba098 Christian Bruel 2024-09-30  160  }
Christian Bruel Jan. 17, 2025, 9:29 a.m. UTC | #2 
Hi Dan,

Thanks for reporting. I think this error is a false positive.

In this situation, the impedance values that are looked-up are ordere 
(the compiler probably doesn't analysis this) so the imp_looup test that 
defines the imp_of must have matched.
Note that the boundaries was checked during probe.

already discussed here:
https://lore.kernel.org/all/ef1ea5da-4344-4c59-8d2b1b52533ef0cd@foss.st.com/

I'll provide a new revision to make this code more friendly with this error

Regards

Christian

On 1/17/25 09:38, Dan Carpenter wrote:
> Hi Christian,
> 
> kernel test robot noticed the following build warnings:
> 
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Christian-Bruel/phy-stm32-Optimize-tuning-values-from-DT/20250113-172435
> base:   v6.13-rc7
> patch link:    https://lore.kernel.org/r/20250113092001.1344151-1-christian.bruel%40foss.st.com
> patch subject: [PATCH v2] phy: stm32: Optimize tuning values from DT.
> config: arm-randconfig-r071-20250117 (https://download.01.org/0day-ci/archive/20250117/202501171619.0XDYDyBZ-lkp@intel.com/config)
> compiler: arm-linux-gnueabi-gcc (GCC) 14.2.0
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> | Closes: https://lore.kernel.org/r/202501171619.0XDYDyBZ-lkp@intel.com/
> 
> New smatch warnings:
> drivers/phy/st/phy-stm32-combophy.c:147 stm32_impedance_tune() error: buffer overflow 'imp_lookup' 8 <= 8 (assuming for loop doesn't break)
> drivers/phy/st/phy-stm32-combophy.c:564 stm32_combophy_probe() warn: passing zero to 'dev_err_probe'
> 
> vim +147 drivers/phy/st/phy-stm32-combophy.c
> 
> 31219ca5436f01 Christian Bruel 2025-01-13  119  static void stm32_impedance_tune(struct stm32_combophy *combophy)
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  120  {
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  121  	u8 imp_of, vswing_of;
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  122  	u32 regval;
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  123
> 31219ca5436f01 Christian Bruel 2025-01-13  124  	if (combophy->microohm) {
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  125  		regval = 0;
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  126  		for (imp_of = 0; imp_of < ARRAY_SIZE(imp_lookup); imp_of++) {
> 31219ca5436f01 Christian Bruel 2025-01-13  127  			if (imp_lookup[imp_of].microohm <= combophy->microohm) {
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  128  				regval = FIELD_PREP(STM32MP25_PCIEPRG_IMPCTRL_OHM, imp_of);
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  129  				break;
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  130  			}
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  131  		}
> 
> If we don't hit the break sttaement above
> 
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  132
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  133  		dev_dbg(combophy->dev, "Set %u micro-ohms output impedance\n",
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  134  			imp_lookup[imp_of].microohm);
>                                                                                     ^^^^^^
> Then this is an out of bounds access.
> 
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  135
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  136  		regmap_update_bits(combophy->regmap, SYSCFG_PCIEPRGCR,
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  137  				   STM32MP25_PCIEPRG_IMPCTRL_OHM,
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  138  				   regval);
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  139  	} else {
> 31219ca5436f01 Christian Bruel 2025-01-13  140  		/* default is 50 ohm */
> 31219ca5436f01 Christian Bruel 2025-01-13  141  		imp_of = 3;
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  142  	}
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  143
> 31219ca5436f01 Christian Bruel 2025-01-13  144  	if (combophy->microvolt) {
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  145  		regval = 0;
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  146  		for (vswing_of = 0; vswing_of < ARRAY_SIZE(imp_lookup[imp_of].vswing); vswing_of++) {
> 31219ca5436f01 Christian Bruel 2025-01-13 @147  			if (imp_lookup[imp_of].vswing[vswing_of] >= combophy->microvolt) {
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  148  				regval = FIELD_PREP(STM32MP25_PCIEPRG_IMPCTRL_VSWING, vswing_of);
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  149  				break;
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  150  			}
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  151  		}
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  152
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  153  		dev_dbg(combophy->dev, "Set %u microvolt swing\n",
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  154  			 imp_lookup[imp_of].vswing[vswing_of]);
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  155
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  156  		regmap_update_bits(combophy->regmap, SYSCFG_PCIEPRGCR,
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  157  				   STM32MP25_PCIEPRG_IMPCTRL_VSWING,
> 2de679ecd724b8 Arnd Bergmann   2024-11-11  158  				   regval);
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  159  	}
> 47e1bb6b4ba098 Christian Bruel 2024-09-30  160  }
>
diff mbox series

Patch

diff --git a/drivers/phy/st/phy-stm32-combophy.c b/drivers/phy/st/phy-stm32-combophy.c
index 49e9fa90a681..5c09c4e48bd0 100644
--- a/drivers/phy/st/phy-stm32-combophy.c
+++ b/drivers/phy/st/phy-stm32-combophy.c
@@ -86,6 +86,10 @@  struct stm32_combophy {
 	struct clk_bulk_data clks[ARRAY_SIZE(combophy_clks)];
 	int num_clks;
 	bool have_pad_clk;
+	bool have_ssc;
+	int rx_eq;
+	u32 microohm;
+	u32 microvolt;
 	unsigned int type;
 	bool is_init;
 	int irq_wakeup;
@@ -112,27 +116,15 @@  static const struct clk_impedance imp_lookup[] = {
 	{ 3999000, { 571000, 648000, 726000, 803000 } }
 };
 
-static int stm32_impedance_tune(struct stm32_combophy *combophy)
+static void stm32_impedance_tune(struct stm32_combophy *combophy)
 {
-	u8 imp_size = ARRAY_SIZE(imp_lookup);
-	u8 vswing_size = ARRAY_SIZE(imp_lookup[0].vswing);
 	u8 imp_of, vswing_of;
-	u32 max_imp = imp_lookup[0].microohm;
-	u32 min_imp = imp_lookup[imp_size - 1].microohm;
-	u32 max_vswing = imp_lookup[imp_size - 1].vswing[vswing_size - 1];
-	u32 min_vswing = imp_lookup[0].vswing[0];
-	u32 val;
 	u32 regval;
 
-	if (!of_property_read_u32(combophy->dev->of_node, "st,output-micro-ohms", &val)) {
-		if (val < min_imp || val > max_imp) {
-			dev_err(combophy->dev, "Invalid value %u for output ohm\n", val);
-			return -EINVAL;
-		}
-
+	if (combophy->microohm) {
 		regval = 0;
 		for (imp_of = 0; imp_of < ARRAY_SIZE(imp_lookup); imp_of++) {
-			if (imp_lookup[imp_of].microohm <= val) {
+			if (imp_lookup[imp_of].microohm <= combophy->microohm) {
 				regval = FIELD_PREP(STM32MP25_PCIEPRG_IMPCTRL_OHM, imp_of);
 				break;
 			}
@@ -145,19 +137,14 @@  static int stm32_impedance_tune(struct stm32_combophy *combophy)
 				   STM32MP25_PCIEPRG_IMPCTRL_OHM,
 				   regval);
 	} else {
-		regmap_read(combophy->regmap, SYSCFG_PCIEPRGCR, &val);
-		imp_of = FIELD_GET(STM32MP25_PCIEPRG_IMPCTRL_OHM, val);
+		/* default is 50 ohm */
+		imp_of = 3;
 	}
 
-	if (!of_property_read_u32(combophy->dev->of_node, "st,output-vswing-microvolt", &val)) {
-		if (val < min_vswing || val > max_vswing) {
-			dev_err(combophy->dev, "Invalid value %u for output vswing\n", val);
-			return -EINVAL;
-		}
-
+	if (combophy->microvolt) {
 		regval = 0;
 		for (vswing_of = 0; vswing_of < ARRAY_SIZE(imp_lookup[imp_of].vswing); vswing_of++) {
-			if (imp_lookup[imp_of].vswing[vswing_of] >= val) {
+			if (imp_lookup[imp_of].vswing[vswing_of] >= combophy->microvolt) {
 				regval = FIELD_PREP(STM32MP25_PCIEPRG_IMPCTRL_VSWING, vswing_of);
 				break;
 			}
@@ -170,8 +157,6 @@  static int stm32_impedance_tune(struct stm32_combophy *combophy)
 				   STM32MP25_PCIEPRG_IMPCTRL_VSWING,
 				   regval);
 	}
-
-	return 0;
 }
 
 static int stm32_combophy_pll_init(struct stm32_combophy *combophy)
@@ -197,7 +182,7 @@  static int stm32_combophy_pll_init(struct stm32_combophy *combophy)
 		cr1_val |= SYSCFG_COMBOPHY_CR1_REFSSPEN;
 	}
 
-	if (of_property_present(combophy->dev->of_node, "st,ssc-on")) {
+	if (combophy->have_ssc) {
 		dev_dbg(combophy->dev, "Enabling clock with SSC\n");
 		cr1_mask |= SYSCFG_COMBOPHY_CR1_SSCEN;
 		cr1_val |= SYSCFG_COMBOPHY_CR1_SSCEN;
@@ -253,24 +238,16 @@  static int stm32_combophy_pll_init(struct stm32_combophy *combophy)
 	reset_control_assert(combophy->phy_reset);
 
 	if (combophy->type == PHY_TYPE_PCIE) {
-		ret = stm32_impedance_tune(combophy);
-		if (ret)
-			goto out_iso;
+		stm32_impedance_tune(combophy);
 
 		cr1_mask |= SYSCFG_COMBOPHY_CR1_REFUSEPAD;
 		cr1_val |= combophy->have_pad_clk ? SYSCFG_COMBOPHY_CR1_REFUSEPAD : 0;
 	}
 
-	if (!of_property_read_u32(combophy->dev->of_node, "st,rx-equalizer", &val)) {
-		dev_dbg(combophy->dev, "Set RX equalizer %u\n", val);
-		if (val > SYSCFG_COMBOPHY_CR4_RX0_EQ) {
-			dev_err(combophy->dev, "Invalid value %u for rx0 equalizer\n", val);
-			ret = -EINVAL;
-			goto out_iso;
-		}
-
+	if (combophy->rx_eq != -1) {
+		dev_dbg(combophy->dev, "Set RX equalizer %u\n", combophy->rx_eq);
 		regmap_update_bits(combophy->regmap, SYSCFG_COMBOPHY_CR4,
-			   SYSCFG_COMBOPHY_CR4_RX0_EQ, val);
+			   SYSCFG_COMBOPHY_CR4_RX0_EQ, combophy->rx_eq);
 	}
 
 	regmap_update_bits(combophy->regmap, SYSCFG_COMBOPHY_CR1, cr1_mask, cr1_val);
@@ -314,9 +291,6 @@  static int stm32_combophy_pll_init(struct stm32_combophy *combophy)
 
 	return 0;
 
-out_iso:
-	reset_control_deassert(combophy->phy_reset);
-
 out:
 	regmap_update_bits(combophy->regmap, SYSCFG_COMBOPHY_CR2,
 			   SYSCFG_COMBOPHY_CR2_ISO_DIS, 0);
@@ -522,6 +496,12 @@  static int stm32_combophy_probe(struct platform_device *pdev)
 	struct stm32_combophy *combophy;
 	struct device *dev = &pdev->dev;
 	struct phy_provider *phy_provider;
+	u8 imp_size = ARRAY_SIZE(imp_lookup);
+	u8 vswing_size = ARRAY_SIZE(imp_lookup[0].vswing);
+	u32 max_imp = imp_lookup[0].microohm;
+	u32 min_imp = imp_lookup[imp_size - 1].microohm;
+	u32 max_vswing = imp_lookup[imp_size - 1].vswing[vswing_size - 1];
+	u32 min_vswing = imp_lookup[0].vswing[0];
 	int ret, irq;
 
 	combophy = devm_kzalloc(dev, sizeof(*combophy), GFP_KERNEL);
@@ -569,6 +549,26 @@  static int stm32_combophy_probe(struct platform_device *pdev)
 						 combophy->irq_wakeup);
 	}
 
+	if (of_property_present(dev->of_node, "st,ssc-on"))
+		combophy->have_ssc = true;
+
+	if (!of_property_read_u32(dev->of_node, "st,rx-equalizer", &combophy->rx_eq)) {
+		if (combophy->rx_eq > SYSCFG_COMBOPHY_CR4_RX0_EQ)
+			return dev_err_probe(dev, combophy->rx_eq,
+					     "Invalid value for rx0 equalizer\n");
+	} else
+		combophy->rx_eq = -1;
+
+	if (!of_property_read_u32(dev->of_node, "st,output-micro-ohms", &combophy->microohm))
+		if (combophy->microohm < min_imp || combophy->microohm > max_imp)
+			return dev_err_probe(dev, combophy->microohm,
+					     "Invalid value for output ohm\n");
+
+	if (!of_property_read_u32(dev->of_node, "st,output-vswing-microvolt", &combophy->microvolt))
+		if (combophy->microvolt < min_vswing || combophy->microvolt > max_vswing)
+			return dev_err_probe(dev, combophy->microvolt,
+					     "Invalid value for output vswing\n");
+
 	ret = devm_pm_runtime_enable(dev);
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to enable pm runtime\n");