[PATCH RESEND 1/3] regulator: max8997: Use simple equation to get selector

[PATCH RESEND 1/3] regulator: max8997: Use simple equation to get selector

[Axel Lin]

It's more efficient to get the best selector by simple equation.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
---
 drivers/regulator/max8997.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/regulator/max8997.c b/drivers/regulator/max8997.c
index 6e7beee..de752da 100644
--- a/drivers/regulator/max8997.c
+++ b/drivers/regulator/max8997.c
@@ -416,7 +416,7 @@ static inline int max8997_get_voltage_proper_val(
 		const struct voltage_map_desc *desc,
 		int min_vol, int max_vol)
 {
-	int i = 0;
+	int i;
 
 	if (desc == NULL)
 		return -EINVAL;
@@ -424,9 +424,10 @@ static inline int max8997_get_voltage_proper_val(
 	if (max_vol < desc->min || min_vol > desc->max)
 		return -EINVAL;
 
-	while (desc->min + desc->step * i < min_vol &&
-			desc->min + desc->step * i < desc->max)
-		i++;
+	if (min_vol < desc->min)
+		min_vol = desc->min;
+
+	i = DIV_ROUND_UP(min_vol - desc->min, desc->step);
 
 	if (desc->min + desc->step * i > max_vol)
 		return -EINVAL;
-- 
1.7.5.4

[PATCH RESEND 2/3] regulator: max8998: Use simple equation to get selector

[Axel Lin]

It's more efficient to get the best selector by simple equation.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
---
 drivers/regulator/max8998.c |   19 ++++++++++---------
 1 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/regulator/max8998.c b/drivers/regulator/max8998.c
index 5890265..90b3193 100644
--- a/drivers/regulator/max8998.c
+++ b/drivers/regulator/max8998.c
@@ -306,8 +306,7 @@ static int max8998_set_voltage_ldo(struct regulator_dev *rdev,
 	int min_vol = min_uV / 1000, max_vol = max_uV / 1000;
 	const struct voltage_map_desc *desc;
 	int ldo = rdev_get_id(rdev);
-	int reg, shift = 0, mask, ret;
-	int i = 0;
+	int reg, shift = 0, mask, ret, i;
 
 	if (ldo >= ARRAY_SIZE(ldo_voltage_map))
 		return -EINVAL;
@@ -319,9 +318,10 @@ static int max8998_set_voltage_ldo(struct regulator_dev *rdev,
 	if (max_vol < desc->min || min_vol > desc->max)
 		return -EINVAL;
 
-	while (desc->min + desc->step*i < min_vol &&
-	       desc->min + desc->step*i < desc->max)
-		i++;
+	if (min_vol < desc->min)
+		min_vol = desc->min;
+
+	i = DIV_ROUND_UP(min_vol - desc->min, desc->step);
 
 	if (desc->min + desc->step*i > max_vol)
 		return -EINVAL;
@@ -359,7 +359,7 @@ static int max8998_set_voltage_buck(struct regulator_dev *rdev,
 	const struct voltage_map_desc *desc;
 	int buck = rdev_get_id(rdev);
 	int reg, shift = 0, mask, ret;
-	int difference = 0, i = 0, j = 0, previous_vol = 0;
+	int difference = 0, i, j = 0, previous_vol = 0;
 	u8 val = 0;
 	static u8 buck1_last_val;
 
@@ -374,9 +374,10 @@ static int max8998_set_voltage_buck(struct regulator_dev *rdev,
 	if (max_vol < desc->min || min_vol > desc->max)
 		return -EINVAL;
 
-	while (desc->min + desc->step*i < min_vol &&
-	       desc->min + desc->step*i < desc->max)
-		i++;
+	if (min_vol < desc->min)
+		min_vol = desc->min;
+
+	i = DIV_ROUND_UP(min_vol - desc->min, desc->step);
 
 	if (desc->min + desc->step*i > max_vol)
 		return -EINVAL;
-- 
1.7.5.4

[PATCH 3/3] regulator: max8997: Remove n_bits from struct voltage_map_desc

[Axel Lin]

The n_bits is only used in max8997_get_voltage_proper_val to check the valid
range for variable i.

Current code already ensures min_vol never greater than desc->max,
which means the variable i always in the valid range:
0 .. (desc->max - desc->min)/desc->step.

Thus we can remove the checking (i >= (1 << desc->n_bits) and then remove
n_bits from struct voltage_map_desc.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
---
 drivers/regulator/max8997.c |   14 +++++---------
 1 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/regulator/max8997.c b/drivers/regulator/max8997.c
index e0fa9b7..e490141 100644
--- a/drivers/regulator/max8997.c
+++ b/drivers/regulator/max8997.c
@@ -68,29 +68,28 @@ struct voltage_map_desc {
 	int min;
 	int max;
 	int step;
-	unsigned int n_bits;
 };
 
 /* Voltage maps in mV */
 static const struct voltage_map_desc ldo_voltage_map_desc = {
-	.min = 800,	.max = 3950,	.step = 50,	.n_bits = 6,
+	.min = 800,	.max = 3950,	.step = 50,
 }; /* LDO1 ~ 18, 21 all */
 
 static const struct voltage_map_desc buck1245_voltage_map_desc = {
-	.min = 650,	.max = 2225,	.step = 25,	.n_bits = 6,
+	.min = 650,	.max = 2225,	.step = 25,
 }; /* Buck1, 2, 4, 5 */
 
 static const struct voltage_map_desc buck37_voltage_map_desc = {
-	.min = 750,	.max = 3900,	.step = 50,	.n_bits = 6,
+	.min = 750,	.max = 3900,	.step = 50,
 }; /* Buck3, 7 */
 
 /* current map in mA */
 static const struct voltage_map_desc charger_current_map_desc = {
-	.min = 200,	.max = 950,	.step = 50,	.n_bits = 4,
+	.min = 200,	.max = 950,	.step = 50,
 };
 
 static const struct voltage_map_desc topoff_current_map_desc = {
-	.min = 50,	.max = 200,	.step = 10,	.n_bits = 4,
+	.min = 50,	.max = 200,	.step = 10,
 };
 
 static const struct voltage_map_desc *reg_voltage_map[] = {
@@ -432,9 +431,6 @@ static inline int max8997_get_voltage_proper_val(
 	if (desc->min + desc->step * i > max_vol)
 		return -EINVAL;
 
-	if (i >= (1 << desc->n_bits))
-		return -EINVAL;
-
 	return i;
 }
 
-- 
1.7.5.4

Re: [PATCH RESEND 1/3] regulator: max8997: Use simple equation to get selector

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 147 bytes --]

On Tue, Apr 10, 2012 at 02:20:03PM +0800, Axel Lin wrote:
> It's more efficient to get the best selector by simple equation.

Applied all, thanks.

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]