Messages in this thread | | | Date | Mon, 14 Feb 2011 23:14:18 +0100 | From | Lars-Peter Clausen <> | Subject | Re: [PATCH 07/14 v3] bq27x00: Cache battery registers |
| |
On 02/14/2011 10:58 PM, Grazvydas Ignotas wrote: > On Mon, Feb 14, 2011 at 5:01 AM, Lars-Peter Clausen <lars@metafoo.de> wrote: >> This patch adds a register cache to the bq27x00 battery driver. >> Usually multiple, if not all, power_supply properties are queried at once, >> for example when an uevent is generated. Since some registers are used by >> multiple properties caching the registers should reduce the number of >> reads. >> >> The cache is valid for 5 seconds this roughly matches the internal update >> interval of the current register for the bq27000/bq27200. >> >> Fast changing properties(*_NOW) which can be obtained by reading a single >> register are not cached. >> >> It will also be used in the follow up patch to check if the battery status >> has been changed since the last update to emit power_supply_changed events. >> >> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> >> --- >> drivers/power/bq27x00_battery.c | 271 +++++++++++++++++++++----------------- >> 1 files changed, 150 insertions(+), 121 deletions(-) >> >> diff --git a/drivers/power/bq27x00_battery.c b/drivers/power/bq27x00_battery.c >> index 44bc76b..dbe3fcb 100644 >> --- a/drivers/power/bq27x00_battery.c >> +++ b/drivers/power/bq27x00_battery.c > > <snip> > >> -static int bq27x00_battery_current(struct bq27x00_device_info *di) >> +static int bq27x00_battery_current(struct bq27x00_device_info *di, >> + union power_supply_propval *val) >> { >> - int ret; >> - int curr = 0; >> - int flags = 0; >> + int curr; >> >> - ret = bq27x00_read(di, BQ27x00_REG_AI, &curr, false); >> - if (ret) { >> - dev_err(di->dev, "error reading current\n"); >> - return 0; >> - } >> + if (di->chip == BQ27500) >> + curr = bq27x00_read(di, BQ27x00_REG_AI, false); >> + else >> + curr = di->cache.current_now; >> + >> + if (curr < 0) >> + return curr; > > This is wrong, as read function returns negative values for bq27500 > when discharging. That's why read function used to pass value through > argument before your series (return value was for error code).
I don't think so. The register is 16bit wide and it is read as a unsigned. So in the non error case bq27x00_read will always return >= 0. The value is later reinterpreted as a signed 16bit.(See the other lines you quoted underneath).
Did you experience any actual problem with current being wrong?
> > Sorry for not noticing this earlier, I only found this now during testing. > >> >> if (di->chip == BQ27500) { >> /* bq27500 returns signed value */ >> - curr = (int)((s16)curr) * 1000; >> + val->intval = (int)((s16)curr) * 1000;
- Lars
| |