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([108.180.130.139]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2dd2cff67aasm59718445ad.79.2026.09.14.22.25.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Sep 2026 22:25:30 -0700 (PDT) From: Babanpreet Singh To: Sebastian Reichel Cc: Hans de Goede , Krzysztof Kozlowski , Marek Szyprowski , Sebastian Krzyszkowiak , Purism Kernel Team , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Babanpreet Singh , kernel test robot , Dan Carpenter Subject: [PATCH] power: supply: max17042_battery: Make the fractional LSB macros safe Date: Tue, 15 Sep 2026 05:25:29 +0000 Message-ID: <20260915052529.7-1-bbnpreetsingh@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The fractional LSB macros expand to a plain division, so they only work when multiplied first and evaluate to 0 anywhere else. Take the value as a macro argument and apply it with mult_frac(). No functional change. Reported-by: kernel test robot Reported-by: Dan Carpenter Closes: https://lore.kernel.org/r/202606062322.TyvCPB3l-lkp@intel.com/ Assisted-by: Claude:claude-opus-5 Assisted-by: Claude:claude-fable-5 Signed-off-by: Babanpreet Singh --- drivers/power/supply/max17042_battery.c | 30 +++++++++++++++---------- 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c index a53970af56cbb..861b5dbc11c1e 100644 --- a/drivers/power/supply/max17042_battery.c +++ b/drivers/power/supply/max17042_battery.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -57,10 +58,15 @@ #define MAX17042_CURRENT_LSB 1562500ll /* 1.5625µV/Rsense */ #define MAX17042_CAPACITY_LSB 5000000ll /* 5.0µVH/Rsense */ -#define MAX17042_TIME_LSB 5625 / 1000 /* s */ -#define MAX17042_VOLTAGE_LSB 625 / 8 /* µV */ -#define MAX17042_RESISTANCE_LSB 1 / 4096 /* Ω */ -#define MAX17042_TEMPERATURE_LSB 1 / 256 /* °C */ +/* + * These LSBs are fractions, so they take their argument rather than + * expanding to a bare "n / d" token sequence, which is only correct in a + * "value * LSB" context. + */ +#define MAX17042_TIME_LSB(val) mult_frac(val, 5625, 1000) /* s */ +#define MAX17042_VOLTAGE_LSB(val) mult_frac(val, 625, 8) /* µV */ +#define MAX17042_RESISTANCE_LSB(val) mult_frac(val, 1, 4096) /* Ω */ +#define MAX17042_TEMPERATURE_LSB(val) mult_frac(val, 1, 256) /* °C */ #define MAX17055_DQACC_DIV 32 #define MAX17055_DPACC_FACTOR 44138 @@ -138,7 +144,7 @@ static int max17042_get_temperature(struct max17042_chip *chip, int *temp) *temp = sign_extend32(data, 15); /* The value is converted into deci-centigrade scale */ - *temp = *temp * 10 * MAX17042_TEMPERATURE_LSB; + *temp = MAX17042_TEMPERATURE_LSB(*temp * 10); return 0; } @@ -214,7 +220,7 @@ static int max17042_get_battery_health(struct max17042_chip *chip, int *health) goto health_error; /* bits [0-3] unused */ - vavg = val * MAX17042_VOLTAGE_LSB; + vavg = MAX17042_VOLTAGE_LSB(val); /* Convert to millivolts */ vavg /= 1000; @@ -223,7 +229,7 @@ static int max17042_get_battery_health(struct max17042_chip *chip, int *health) goto health_error; /* bits [0-3] unused */ - vbatt = val * MAX17042_VOLTAGE_LSB; + vbatt = MAX17042_VOLTAGE_LSB(val); /* Convert to millivolts */ vbatt /= 1000; @@ -330,21 +336,21 @@ static int max17042_get_property(struct power_supply *psy, if (ret < 0) return ret; - val->intval = data * MAX17042_VOLTAGE_LSB; + val->intval = MAX17042_VOLTAGE_LSB(data); break; case POWER_SUPPLY_PROP_VOLTAGE_AVG: ret = regmap_read(map, MAX17042_AvgVCELL, &data); if (ret < 0) return ret; - val->intval = data * MAX17042_VOLTAGE_LSB; + val->intval = MAX17042_VOLTAGE_LSB(data); break; case POWER_SUPPLY_PROP_VOLTAGE_OCV: ret = regmap_read(map, MAX17042_OCVInternal, &data); if (ret < 0) return ret; - val->intval = data * MAX17042_VOLTAGE_LSB; + val->intval = MAX17042_VOLTAGE_LSB(data); break; case POWER_SUPPLY_PROP_CAPACITY: if (chip->enable_current_sense) @@ -473,7 +479,7 @@ static int max17042_get_property(struct power_supply *psy, if (data == U16_MAX) return -ENODATA; - val->intval = data * MAX17042_TIME_LSB; + val->intval = MAX17042_TIME_LSB(data); break; case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW: if (chip->chip_type != MAXIM_DEVICE_TYPE_MAX17055 && @@ -488,7 +494,7 @@ static int max17042_get_property(struct power_supply *psy, if (data == U16_MAX) return -ENODATA; - val->intval = data * MAX17042_TIME_LSB; + val->intval = MAX17042_TIME_LSB(data); break; default: return -EINVAL; base-commit: 4fc88ba435dadbc05990951e3f3fbd8ccd2df140 -- 2.43.0