linux-kernel - [PATCH v4 1/5] power: supply: max1720x correct capacity computation

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Message-Id: <20250523-b4-gs101_max77759_fg-v4-1-b49904e35a34@uclouvain.be>
Date: Fri, 23 May 2025 14:51:44 +0200
From: Thomas Antoine via B4 Relay <devnull+t.antoine.uclouvain.be@...nel.org>
To: Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Dimitri Fedrau <dima.fedrau@...il.com>, 
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
 Peter Griffin <peter.griffin@...aro.org>, 
 André Draszik <andre.draszik@...aro.org>, 
 Tudor Ambarus <tudor.ambarus@...aro.org>, 
 Alim Akhtar <alim.akhtar@...sung.com>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-samsung-soc@...r.kernel.org, Thomas Antoine <t.antoine@...ouvain.be>
Subject: [PATCH v4 1/5] power: supply: max1720x correct capacity
 computation

From: Thomas Antoine <t.antoine@...ouvain.be>

>From the datasheet of the MAX17201/17205, the LSB should be
"5.0μVh/RSENSE". The current computation sets it at 0.5mAh=5.0μVh/10mOhm
which does not take into account the value of rsense which can be
different from 10mOhm.

Change the computation to fit the specs.

Signed-off-by: Thomas Antoine <t.antoine@...ouvain.be>
---
 drivers/power/supply/max1720x_battery.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/power/supply/max1720x_battery.c b/drivers/power/supply/max1720x_battery.c
index ea3912fd1de8bfd0d029c16f276316d06e1b105c..68b5314ecf3a234f906ec8fe400e586855b69cd9 100644
--- a/drivers/power/supply/max1720x_battery.c
+++ b/drivers/power/supply/max1720x_battery.c
@@ -288,9 +288,10 @@ static int max172xx_voltage_to_ps(unsigned int reg)
 	return reg * 1250;	/* in uV */
 }
 
-static int max172xx_capacity_to_ps(unsigned int reg)
+static int max172xx_capacity_to_ps(unsigned int reg,
+				   struct max1720x_device_info *info)
 {
-	return reg * 500;	/* in uAh */
+	return reg * (500000 / info->rsense);	/* in uAh */
 }
 
 /*
@@ -394,11 +395,11 @@ static int max1720x_battery_get_property(struct power_supply *psy,
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
 		ret = regmap_read(info->regmap, MAX172XX_DESIGN_CAP, &reg_val);
-		val->intval = max172xx_capacity_to_ps(reg_val);
+		val->intval = max172xx_capacity_to_ps(reg_val, info);
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_AVG:
 		ret = regmap_read(info->regmap, MAX172XX_REPCAP, &reg_val);
-		val->intval = max172xx_capacity_to_ps(reg_val);
+		val->intval = max172xx_capacity_to_ps(reg_val, info);
 		break;
 	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
 		ret = regmap_read(info->regmap, MAX172XX_TTE, &reg_val);
@@ -422,7 +423,7 @@ static int max1720x_battery_get_property(struct power_supply *psy,
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_FULL:
 		ret = regmap_read(info->regmap, MAX172XX_FULL_CAP, &reg_val);
-		val->intval = max172xx_capacity_to_ps(reg_val);
+		val->intval = max172xx_capacity_to_ps(reg_val, info);
 		break;
 	case POWER_SUPPLY_PROP_MODEL_NAME:
 		ret = regmap_read(info->regmap, MAX172XX_DEV_NAME, &reg_val);

-- 
2.49.0