Re: [PATCH v2 4/4] power: bq25890_charger.c: Read back the current battery voltage

From: Angus Ainslie
Date: Fri Jul 27 2018 - 11:30:35 EST


On 2018-07-26 01:03, Krzysztof Kozlowski wrote:
On 25 July 2018 at 21:46, Angus Ainslie (Purism) <angus@xxxxxxxx> wrote:
The part has the capability of reading the current battery voltage

Signed-off-by: Angus Ainslie (Purism) <angus@xxxxxxxx>
---
drivers/power/supply/bq25890_charger.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/drivers/power/supply/bq25890_charger.c b/drivers/power/supply/bq25890_charger.c
index f4cf2987996b..60ccd6c2b7ad 100644
--- a/drivers/power/supply/bq25890_charger.c
+++ b/drivers/power/supply/bq25890_charger.c
@@ -464,6 +464,20 @@ static int bq25890_power_supply_get_property(struct power_supply *psy,
val->intval = bq25890_find_val(bq->init_data.iterm, TBL_ITERM);
break;

+ case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+ if (!state.online) {
+ val->intval = 0;
+ break;
+ }

You use state from cached value (from last interrupt) but the voltage
is read directly from registers. The driver follows this convention in
few other places so maybe it is okay. It depends how accurately the
interrupts are generated - on every change? IOW, is always guaranteed
that state will be consistent with values read below?


Well I shouldn't even be checking state here as the VOLTAGE_NOW should be valid without it. I'll drop that check.

( Krzysztof sorry for the duplicate email )

Best regards,
Krzysztof

+
+ ret = bq25890_field_read(bq, F_SYSV); /* read measured value */
+ if (ret < 0)
+ return ret;
+
+ /* converted_val = 2.304V + ADC_val * 20mV (table 10.3.15) */
+ val->intval = 2304000 + ret * 20000;
+ break;
+
default:
return -EINVAL;
}
@@ -672,6 +686,7 @@ static enum power_supply_property bq25890_power_supply_props[] = {
POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE,
POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE_MAX,
POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT,
+ POWER_SUPPLY_PROP_VOLTAGE_NOW,
};

static char *bq25890_charger_supplied_to[] = {
--
2.17.1