Re: [RFC][PATCH] ACPI: battery: add power_{now, avg} properties to power_class

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday, 16 of December 2008, Alexey Starikovskiy wrote:
> Rafael J. Wysocki wrote:
> > Hi,
> > 
> > On Monday, 15 of December 2008, Alexey Starikovskiy wrote:
> >> ACPI has smart batteries, which work in units of energy and measure
> >> rate of (dis)charge as power, thus it is not appropriate to export it
> >> as a current_now.
> >>
> >> Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
> >> ---
> >>
> >>  drivers/acpi/battery.c             |    3 ++-
> >>  drivers/acpi/sbs.c                 |    6 ++++--
> >>  drivers/power/power_supply_sysfs.c |    2 ++
> >>  include/linux/power_supply.h       |    2 ++
> >>  4 files changed, 10 insertions(+), 3 deletions(-)
> >>
> >>
> >> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> >> index 1423b0c..88f1fb5 100644
> >> --- a/drivers/acpi/battery.c
> >> +++ b/drivers/acpi/battery.c
> >> @@ -173,6 +173,7 @@ static int acpi_battery_get_property(struct power_supply *psy,
> >>  		val->intval = battery->voltage_now * 1000;
> >>  		break;
> >>  	case POWER_SUPPLY_PROP_CURRENT_NOW:
> >> +	case POWER_SUPPLY_PROP_POWER_NOW:
> >>  		val->intval = battery->current_now * 1000;
> >>  		break;
> >>  	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
> >> @@ -223,7 +224,7 @@ static enum power_supply_property energy_battery_props[] = {
> >>  	POWER_SUPPLY_PROP_TECHNOLOGY,
> >>  	POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
> >>  	POWER_SUPPLY_PROP_VOLTAGE_NOW,
> >> -	POWER_SUPPLY_PROP_CURRENT_NOW,
> >> +	POWER_SUPPLY_PROP_POWER_NOW,
> >>  	POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
> >>  	POWER_SUPPLY_PROP_ENERGY_FULL,
> >>  	POWER_SUPPLY_PROP_ENERGY_NOW,
> >> diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
> >> index 6050ce4..994c04e 100644
> >> --- a/drivers/acpi/sbs.c
> >> +++ b/drivers/acpi/sbs.c
> >> @@ -224,10 +224,12 @@ static int acpi_sbs_battery_get_property(struct power_supply *psy,
> >>  				acpi_battery_vscale(battery) * 1000;
> >>  		break;
> >>  	case POWER_SUPPLY_PROP_CURRENT_NOW:
> >> +	case POWER_SUPPLY_PROP_POWER_NOW:
> >>  		val->intval = abs(battery->current_now) *
> >>  				acpi_battery_ipscale(battery) * 1000;
> > 
> > Please introduce another field called 'battery->power_now' for this purpose.
> > Otherwise, confusion is guaranteed to ensue.
> How about 'battery->rate_now' for both cases? All other fields are re-used
> as well, and it did not cause any confusion.  Probably no-one ever looked at
> this code.

Well, they are called 'capacity_*', which doesn't imply any particular units,
while 'current_*' does.

Anyway, 'battery->rate_now' would be better than 'battery->current_now'.
What about 'battery->capacity_flow'?

> 
> > 
> >>  		break;
> >>  	case POWER_SUPPLY_PROP_CURRENT_AVG:
> >> +	case POWER_SUPPLY_PROP_POWER_AVG:
> >>  		val->intval = abs(battery->current_avg) *
> >>  				acpi_battery_ipscale(battery) * 1000;
> > 
> > Same here.
> > 
> > Also, as per our IRC conversation, I'd like 'current_now' to be reported even
> > if energy units are used, at least for some time, to give a chance to the user
> > land to switch to 'power_now' and 'power_avg' without pain.
> To clarify, you suggest that "current_now" will report same value 
> as "power_now" in case of energy units?

Yes, with a comment why that is so (ie. because of the userland doing stupid
things).

> > You can put information about that into
> > Documentation/feature-removal-schedule.txt and say that after 2.6.29
> > 'current_now' will no longer be reported when energy units are used.
> Sounds good.

OK

Thanks,
Rafael