linux-kernel - [PATCH 2/4] power: max17042_battery: Improve accuracy of current_now and current

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Message-ID: <4526762.6nKOPmpm47@pliszka>
Date:   Wed, 25 Nov 2020 05:46:17 +0100
From:   Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>
To:     Sebastian Reichel <sre@...nel.org>
Cc:     Geordan Neukum <gneukum1@...il.com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel@...i.sm
Subject: [PATCH 2/4] power: max17042_battery: Improve accuracy of current_now and current_avg readings

Dividing 1562500 by r_sns value usually doesn't result in an integer.

Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>
---
 drivers/power/supply/max17042_battery.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
index 2e9672fe4df1..86adccb0f32d 100644
--- a/drivers/power/supply/max17042_battery.c
+++ b/drivers/power/supply/max17042_battery.c
@@ -395,8 +395,8 @@ static int max17042_get_property(struct power_supply *psy,
 			if (ret < 0)
 				return ret;
 
-			val->intval = sign_extend32(data, 15);
-			val->intval *= 1562500 / chip->pdata->r_sns;
+			data64 = sign_extend64(data, 15) * 1562500ll;
+			val->intval = div_s64(data64, chip->pdata->r_sns);
 		} else {
 			return -EINVAL;
 		}
@@ -407,8 +407,8 @@ static int max17042_get_property(struct power_supply *psy,
 			if (ret < 0)
 				return ret;
 
-			val->intval = sign_extend32(data, 15);
-			val->intval *= 1562500 / chip->pdata->r_sns;
+			data64 = sign_extend64(data, 15) * 1562500ll;
+			val->intval = div_s64(data64, chip->pdata->r_sns);
 		} else {
 			return -EINVAL;
 		}
-- 
2.29.2