linux-kernel - [PATCH 3/6] power: supply: sc27xx: Fix the the accuracy issue of coulomb calculation

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Date:   Wed, 31 Jul 2019 18:00:25 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     sre@...nel.org
Cc:     orsonzhai@...il.com, zhang.lyra@...il.com, yuanjiang.yu@...soc.com,
        baolin.wang@...aro.org, vincent.guittot@...aro.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/6] power: supply: sc27xx: Fix the the accuracy issue of coulomb calculation

From: Yuanjiang Yu <yuanjiang.yu@...soc.com>

The Spreadtrum fuel gauge will multiply by 2 for counting the coulomb
counter to improve the accuracy, which means the value saved in fuel
gauge is: coulomb counter * 2 * 1000ma_adc. Thus fix the conversion
formular to improve the accuracy of calculating the battery capacity.

Signed-off-by: Yuanjiang Yu <yuanjiang.yu@...soc.com>
Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
---
 drivers/power/supply/sc27xx_fuel_gauge.c |   11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/power/supply/sc27xx_fuel_gauge.c b/drivers/power/supply/sc27xx_fuel_gauge.c
index ca7b73e..ab3afa1 100644
--- a/drivers/power/supply/sc27xx_fuel_gauge.c
+++ b/drivers/power/supply/sc27xx_fuel_gauge.c
@@ -326,8 +326,6 @@ static int sc27xx_fgu_set_clbcnt(struct sc27xx_fgu_data *data, int clbcnt)
 {
 	int ret;
 
-	clbcnt *= SC27XX_FGU_SAMPLE_HZ;
-
 	ret = regmap_update_bits(data->regmap,
 				 data->base + SC27XX_FGU_CLBCNT_SETL,
 				 SC27XX_FGU_CLBCNT_MASK, clbcnt);
@@ -362,7 +360,6 @@ static int sc27xx_fgu_get_clbcnt(struct sc27xx_fgu_data *data, int *clb_cnt)
 
 	*clb_cnt = ccl & SC27XX_FGU_CLBCNT_MASK;
 	*clb_cnt |= (cch & SC27XX_FGU_CLBCNT_MASK) << SC27XX_FGU_CLBCNT_SHIFT;
-	*clb_cnt /= SC27XX_FGU_SAMPLE_HZ;
 
 	return 0;
 }
@@ -380,10 +377,10 @@ static int sc27xx_fgu_get_capacity(struct sc27xx_fgu_data *data, int *cap)
 
 	/*
 	 * Convert coulomb counter to delta capacity (mAh), and set multiplier
-	 * as 100 to improve the precision.
+	 * as 10 to improve the precision.
 	 */
-	temp = DIV_ROUND_CLOSEST(delta_clbcnt, 360);
-	temp = sc27xx_fgu_adc_to_current(data, temp);
+	temp = DIV_ROUND_CLOSEST(delta_clbcnt * 10, 36 * SC27XX_FGU_SAMPLE_HZ);
+	temp = sc27xx_fgu_adc_to_current(data, temp / 1000);
 
 	/*
 	 * Convert to capacity percent of the battery total capacity,
@@ -790,7 +787,7 @@ static int sc27xx_fgu_cap_to_clbcnt(struct sc27xx_fgu_data *data, int capacity)
 	 * Convert current capacity (mAh) to coulomb counter according to the
 	 * formula: 1 mAh =3.6 coulomb.
 	 */
-	return DIV_ROUND_CLOSEST(cur_cap * 36 * data->cur_1000ma_adc, 10);
+	return DIV_ROUND_CLOSEST(cur_cap * 36 * data->cur_1000ma_adc * SC27XX_FGU_SAMPLE_HZ, 10);
 }
 
 static int sc27xx_fgu_calibration(struct sc27xx_fgu_data *data)
-- 
1.7.9.5