linux-kernel - [PATCH 2/2] hwmon: (ina2xx) use DIV_ROUND

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Date:	Mon, 12 Jan 2015 14:47:22 +0100
From:	Bartosz Golaszewski <bgolaszewski@...libre.com>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Benoit Cousson <bcousson@...libre.com>,
	Patrick Titiano <ptitiano@...libre.com>,
	LM Sensors <lm-sensors@...sensors.org>,
	Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH 2/2] hwmon: (ina2xx) use DIV_ROUND_CLOSEST() to avoid rounding errors

Use DIV_ROUND_CLOSEST() when dealing with the calibration values to make the
calculations less error prone.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
---
 drivers/hwmon/ina2xx.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index ae110c5..611ec4e 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -186,8 +186,11 @@ static void ina226_set_update_interval(struct ina2xx_data *data)
 
 static int ina2xx_calibrate(struct ina2xx_data *data)
 {
-	return i2c_smbus_write_word_swapped(data->client, INA2XX_CALIBRATION,
-			data->config->calibration_factor / data->rshunt);
+	u16 val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
+				    data->rshunt);
+
+	return i2c_smbus_write_word_swapped(data->client,
+					    INA2XX_CALIBRATION, val);
 }
 
 /*
@@ -307,7 +310,8 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg)
 		val = (s16)data->regs[reg];
 		break;
 	case INA2XX_CALIBRATION:
-		val = data->config->calibration_factor / data->regs[reg];
+		val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
+					data->regs[reg]);
 		break;
 	default:
 		/* programmer goofed */
-- 
2.1.3

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