* [PATCH] power: max8925_power: Fix incorrect voltage and current calculation
@ 2011-08-26 20:28 Philip Rakity
2011-08-26 23:11 ` Haojian Zhuang
0 siblings, 1 reply; 2+ messages in thread
From: Philip Rakity @ 2011-08-26 20:28 UTC (permalink / raw)
To: linux-kernel, Haojian Zhuang
The datasheet indicates a 12 bit value is returned for i2c
registers for voltage and current. Code was assuming 8 bits.
But default for chip is 12 bit return value.
Voltage is returned in 2mV units -- adjust to return as uV
per linux power spec
Adjust current calculation to return units in uA
*** NOT POSSIBLE TO VALIDATE THIS since my h/w does not have
current hooked up to 8925 *****
Signed-off-by: Philip Rakity <prakity@marvell.com>
---
drivers/power/max8925_power.c | 13 ++++++-------
1 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/power/max8925_power.c b/drivers/power/max8925_power.c
index 29b5d2c..5e4e046 100644
--- a/drivers/power/max8925_power.c
+++ b/drivers/power/max8925_power.c
@@ -190,7 +190,7 @@ static int start_measure(struct max8925_power_info *info, int type)
}
max8925_bulk_read(info->adc, meas_reg, 2, buf);
- ret = (buf[0] << 4) | (buf[1] >> 4);
+ ret = ((buf[0]<<8) | buf[1]) >> 4;
return ret;
}
@@ -210,7 +210,7 @@ static int max8925_ac_get_prop(struct power_supply *psy,
if (info->ac_online) {
ret = start_measure(info, MEASURE_VCHG);
if (ret >= 0) {
- val->intval = ret << 1; /* unit is mV */
+ val->intval = ret * 2000; /* unit is uV */
goto out;
}
}
@@ -244,7 +244,7 @@ static int max8925_usb_get_prop(struct power_supply *psy,
if (info->usb_online) {
ret = start_measure(info, MEASURE_VCHG);
if (ret >= 0) {
- val->intval = ret << 1; /* unit is mV */
+ val->intval = ret * 2000; /* unit is uV */
goto out;
}
}
@@ -268,7 +268,6 @@ static int max8925_bat_get_prop(struct power_supply *psy,
union power_supply_propval *val)
{
struct max8925_power_info *info = dev_get_drvdata(psy->dev->parent);
- long long int tmp = 0;
int ret = 0;
switch (psp) {
@@ -279,7 +278,7 @@ static int max8925_bat_get_prop(struct power_supply *psy,
if (info->bat_online) {
ret = start_measure(info, MEASURE_VMBATT);
if (ret >= 0) {
- val->intval = ret << 1; /* unit is mV */
+ val->intval = ret * 2000; /* unit is uV */
ret = 0;
break;
}
@@ -290,8 +289,8 @@ static int max8925_bat_get_prop(struct power_supply *psy,
if (info->bat_online) {
ret = start_measure(info, MEASURE_ISNS);
if (ret >= 0) {
- tmp = (long long int)ret * 6250 / 4096 - 3125;
- ret = (int)tmp;
+ /* assume r_sns is 0.02 */
+ ret = ((ret * 6250) - 3125) /* uA */;
val->intval = 0;
if (ret > 0)
val->intval = ret; /* unit is mA */
--
1.7.6
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] power: max8925_power: Fix incorrect voltage and current calculation
2011-08-26 20:28 [PATCH] power: max8925_power: Fix incorrect voltage and current calculation Philip Rakity
@ 2011-08-26 23:11 ` Haojian Zhuang
0 siblings, 0 replies; 2+ messages in thread
From: Haojian Zhuang @ 2011-08-26 23:11 UTC (permalink / raw)
To: Philip Rakity, David Woodhouse, cbou; +Cc: linux-kernel
On Sat, Aug 27, 2011 at 4:28 AM, Philip Rakity <prakity@marvell.com> wrote:
>
> The datasheet indicates a 12 bit value is returned for i2c
> registers for voltage and current. Code was assuming 8 bits.
> But default for chip is 12 bit return value.
>
> Voltage is returned in 2mV units -- adjust to return as uV
> per linux power spec
>
> Adjust current calculation to return units in uA
> *** NOT POSSIBLE TO VALIDATE THIS since my h/w does not have
> current hooked up to 8925 *****
>
> Signed-off-by: Philip Rakity <prakity@marvell.com>
> ---
> drivers/power/max8925_power.c | 13 ++++++-------
> 1 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/power/max8925_power.c b/drivers/power/max8925_power.c
> index 29b5d2c..5e4e046 100644
> --- a/drivers/power/max8925_power.c
> +++ b/drivers/power/max8925_power.c
> @@ -190,7 +190,7 @@ static int start_measure(struct max8925_power_info *info, int type)
> }
>
> max8925_bulk_read(info->adc, meas_reg, 2, buf);
> - ret = (buf[0] << 4) | (buf[1] >> 4);
> + ret = ((buf[0]<<8) | buf[1]) >> 4;
>
> return ret;
> }
> @@ -210,7 +210,7 @@ static int max8925_ac_get_prop(struct power_supply *psy,
> if (info->ac_online) {
> ret = start_measure(info, MEASURE_VCHG);
> if (ret >= 0) {
> - val->intval = ret << 1; /* unit is mV */
> + val->intval = ret * 2000; /* unit is uV */
> goto out;
> }
> }
> @@ -244,7 +244,7 @@ static int max8925_usb_get_prop(struct power_supply *psy,
> if (info->usb_online) {
> ret = start_measure(info, MEASURE_VCHG);
> if (ret >= 0) {
> - val->intval = ret << 1; /* unit is mV */
> + val->intval = ret * 2000; /* unit is uV */
> goto out;
> }
> }
> @@ -268,7 +268,6 @@ static int max8925_bat_get_prop(struct power_supply *psy,
> union power_supply_propval *val)
> {
> struct max8925_power_info *info = dev_get_drvdata(psy->dev->parent);
> - long long int tmp = 0;
> int ret = 0;
>
> switch (psp) {
> @@ -279,7 +278,7 @@ static int max8925_bat_get_prop(struct power_supply *psy,
> if (info->bat_online) {
> ret = start_measure(info, MEASURE_VMBATT);
> if (ret >= 0) {
> - val->intval = ret << 1; /* unit is mV */
> + val->intval = ret * 2000; /* unit is uV */
> ret = 0;
> break;
> }
> @@ -290,8 +289,8 @@ static int max8925_bat_get_prop(struct power_supply *psy,
> if (info->bat_online) {
> ret = start_measure(info, MEASURE_ISNS);
> if (ret >= 0) {
> - tmp = (long long int)ret * 6250 / 4096 - 3125;
> - ret = (int)tmp;
> + /* assume r_sns is 0.02 */
> + ret = ((ret * 6250) - 3125) /* uA */;
> val->intval = 0;
> if (ret > 0)
> val->intval = ret; /* unit is mA */
> --
> 1.7.6
>
Loop maintainer
^ permalink raw reply [flat|nested] 2+ messages in thread
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2011-08-26 20:28 [PATCH] power: max8925_power: Fix incorrect voltage and current calculation Philip Rakity
2011-08-26 23:11 ` Haojian Zhuang
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