shutdown machine when li-ion battery goes below 3V

Hi!

What about something like this? N900 will drain the battery down to system crash, which is quite uncool.

Quoted 4 lines · Pavel Machek

Hi!

What about something like this? N900 will drain the battery down to system crash, which is quite uncool.

Can't we make that generic and configurable for the voltage somehow?

Also, the shutdown voltage can depend on external devices connected. It could be for example 3.3V depending on eMMC on some devices while devices with no eMMC could have it at 3.0V.

Quoted 3 lines · Tony Lindgren

Also, the shutdown voltage can depend on external devices connected. It could be for example 3.3V depending on eMMC on some devices while devices with no eMMC could have it at 3.0V.

Actually, I'd like to shutdown at 3.3V or more (like 3.5V), because going below that is pretty mean to the battery. But if I set threshold too high, GSM activity will push it below that for a very short while, and I'll shutdown too soon.

Ideas welcome...

Quoted 10 lines · On Monday 24 October 2016 23:41:52 Pavel Machek wrote:

Quoted 3 lines · Tony Lindgren

Also, the shutdown voltage can depend on external devices connected. It could be for example 3.3V depending on eMMC on some devices while devices with no eMMC could have it at 3.0V.

Actually, I'd like to shutdown at 3.3V or more (like 3.5V), because going below that is pretty mean to the battery. But if I set threshold too high, GSM activity will push it below that for a very short while, and I'll shutdown too soon.

Quoted 1 line

Ideas welcome...

bq27x00 has EDVF flag which means that battery is empty. Maemo with bq27x00 driver is configured to issue system shutdown when EDVF is set.

Maybe kernel should issue emergency shutdown e.g. after minute or two after EDVF flag is set?

Quoted 16 lines · Pali Roh?r

Quoted 11 lines · On Monday 24 October 2016 23:41:52 Pavel Machek wrote:

Quoted 3 lines · Tony Lindgren

Also, the shutdown voltage can depend on external devices connected. It could be for example 3.3V depending on eMMC on some devices while devices with no eMMC could have it at 3.0V.

Actually, I'd like to shutdown at 3.3V or more (like 3.5V), because going below that is pretty mean to the battery. But if I set threshold too high, GSM activity will push it below that for a very short while, and I'll shutdown too soon.

Ideas welcome...

bq27x00 has EDVF flag which means that battery is empty. Maemo with bq27x00 driver is configured to issue system shutdown when EDVF is set.

Quoted 2 lines

Maybe kernel should issue emergency shutdown e.g. after minute or two after EDVF flag is set?

Thanks for pointer.

EDVF seems to be exposed as health. ... but only if battery is calibrated, AFAICT.

 if (has_ci_flag && (cache.flags & BQ27000_FLAG_CI)) {
      dev_info_once(di->dev, "battery is not calibrated! ignoring capacity values\n");

      ...
      cache.health = -ENODATA;

Plus, it prioritizes battery cold over battery dead. IMO we don't need to shutdown on battery cold (we just may not charge the battery), but we need to shutdown on battery dead.

So something like this?

Pavel

Signed-off-by Pavel Machek <[email protected]>

drivers/power/supply/bq27xxx_battery.c +0 -0

index 8eb2f8f..5ddf6d7 100644
@@ -680,10 +680,10 @@ static int bq27xxx_battery_read_health(struct bq27xxx_device_info *di)
 	/* Unlikely but important to return first */
 	if (unlikely(bq27xxx_battery_overtemp(di, flags)))

Quoted 17 lines · On Tuesday 25 October 2016 12:24:35 Pavel Machek wrote:

Quoted 16 lines · Pali Roh?r

Quoted 11 lines · On Monday 24 October 2016 23:41:52 Pavel Machek wrote:

Quoted 3 lines · Tony Lindgren

Also, the shutdown voltage can depend on external devices connected. It could be for example 3.3V depending on eMMC on some devices while devices with no eMMC could have it at 3.0V.

Actually, I'd like to shutdown at 3.3V or more (like 3.5V), because going below that is pretty mean to the battery. But if I set threshold too high, GSM activity will push it below that for a very short while, and I'll shutdown too soon.

Ideas welcome...

bq27x00 has EDVF flag which means that battery is empty. Maemo with bq27x00 driver is configured to issue system shutdown when EDVF is set.

Quoted 7 lines

Quoted 2 lines

Maybe kernel should issue emergency shutdown e.g. after minute or two after EDVF flag is set?

Thanks for pointer.

EDVF seems to be exposed as health. ... but only if battery is calibrated, AFAICT.

No, EDVF is available also for uncalibrated battery. There are EDV1 and EDVF flags. Both are set based on battery voltage and some other parameters from bq EEPROM.

Quoted 2 lines

 if (has_ci_flag && (cache.flags & BQ27000_FLAG_CI)) {
      dev_info_once(di->dev, "battery is not calibrated! ignoring capacity values\n");

Yes, it ignores only capacity values (which needs calibration), not those raw flags which works also without calibration.

Quoted 2 lines

      ...
      cache.health = -ENODATA;

Take a look at code. Health is not read from hardware unless battery is calibrated.

Quoted 4 lines · Pavel Machek

Hi!

What about something like this? N900 will drain the battery down to system crash, which is quite uncool.

Can't we make that generic and configurable for the voltage somehow?

Also, the shutdown voltage can depend on external devices connected. It could be for example 3.3V depending on eMMC on some devices while devices with no eMMC could have it at 3.0V.

Quoted 11 lines · Tony Lindgren

Quoted 4 lines · Pavel Machek

Hi!

What about something like this? N900 will drain the battery down to system crash, which is quite uncool.

Can't we make that generic and configurable for the voltage somehow?

Also, the shutdown voltage can depend on external devices connected. It could be for example 3.3V depending on eMMC on some devices while devices with no eMMC could have it at 3.0V.

Actually, do we need to make it configurable? It looks like we should respect hardware telling us battery is dead, and only use (low) hardcoded voltages as a fallback.

Currently patch looks like this. generic_protect() should work for other batteries drivers, too.

Pavel

drivers/power/supply/bq27xxx_battery.c +13 -2

index 0fe278b..04094ad 100644
@@ -46,6 +46,7 @@
 #include <linux/delay.h>
 #include <linux/platform_device.h>
 #include <linux/power_supply.h>
+#include <linux/reboot.h>
 #include <linux/slab.h>
 #include <linux/of.h>
 

@@ -679,10 +680,10 @@ static int bq27xxx_battery_read_health(struct bq27xxx_device_info *di)
 	/* Unlikely but important to return first */
 	if (unlikely(bq27xxx_battery_overtemp(di, flags)))
 		return POWER_SUPPLY_HEALTH_OVERHEAT;
-	if (unlikely(bq27xxx_battery_undertemp(di, flags)))
-		return POWER_SUPPLY_HEALTH_COLD;
 	if (unlikely(bq27xxx_battery_dead(di, flags)))
 		return POWER_SUPPLY_HEALTH_DEAD;
+	if (unlikely(bq27xxx_battery_undertemp(di, flags)))
+		return POWER_SUPPLY_HEALTH_COLD;
 
 	return POWER_SUPPLY_HEALTH_GOOD;
 }

@@ -740,6 +741,49 @@ void bq27xxx_battery_update(struct bq27xxx_device_info *di)
 }
 EXPORT_SYMBOL_GPL(bq27xxx_battery_update);
 
+static void shutdown(char *reason)
+{
+	pr_alert("%s Forcing shutdown\n", reason);
+	orderly_poweroff(true);
+}
+
+static int generic_protect(struct power_supply *psy)
+{
+	union power_supply_propval val;
+	int res;

drivers/power/supply/bq27xxx_battery.c +9 -0

+	res = psy->desc->get_property(psy, POWER_SUPPLY_PROP_VOLTAGE_NOW, &val);
+	if (res)
+		return res;
+	mV = val.intval / 1000;
+
+	if (mV < 2950)
+		shutdown("Battery below 2.95V.");
+
+	res = psy->desc->get_property(psy, POWER_SUPPLY_PROP_CURRENT_NOW, &val);

drivers/power/supply/bq27xxx_battery.c +4 -0

+	return 0;
+}
+
 static void bq27xxx_battery_poll(struct work_struct *work)
 {
 	struct bq27xxx_device_info *di =

@@ -747,6 +791,7 @@ static void bq27xxx_battery_poll(struct work_struct *work)
 				     work.work);
 
 	bq27xxx_battery_update(di);
+	generic_protect(di->bat);
 
 	if (poll_interval > 0)
 		schedule_delayed_work(&di->work, poll_interval * HZ);