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SubjectRe: [PATCH 2/4] power_supply: Introduce generic psy charging driver
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On Fri, Mar 7, 2014 at 9:10 PM, Pavel Machek <pavel@ucw.cz> wrote:
> On Fri 2014-03-07 11:04:59, Linus Walleij wrote:
>> On Fri, Feb 28, 2014 at 6:01 PM, Pavel Machek <pavel@ucw.cz> wrote:
>> > On Thu 2014-02-27 21:08:01, Linus Walleij wrote:
>> >> On Thu, Feb 20, 2014 at 6:53 AM, Jenny TC <jenny.tc@intel.com> wrote:
>> >>
>> >> > +++ b/include/linux/power/power_supply_charger.h
>> >>
>> >> > +#define MAX_CUR_VOLT_SAMPLES 3
>> >> > +#define DEF_CUR_VOLT_SAMPLE_JIFF (30*HZ)
>> >>
>> >> Why are things defined in Jiffies like this insead of seconds, milliseconds
>> >> etc? This will vary with the current operating frequency of the system,
>> >> why should physical measurements do that?
>> >
>> > It is actually ok. The define is relative to jiffies, and that's what
>> > interface expects.
>>
>> So consider the option that the interface is wrong.
>>
>> Stating something like a sample period in system-specific jiffies
>> instead of period time T is just weird. What control systems
>> guy would understand this?
>
> 30*HZ means 30 seconds in the kernel... what is hard to understand
> about it?

Well I might be picky, but since it is a charging algorithm dealing with
ampères, volts, constant-current/constant-voltage, watchdogs and
timeouts, all stated in SI units, it would be nice if all such constants
were specified in simple units instead of kernel-specific terms.

One reason is that this kind of code actually needs review from
non-programmers, people like chemists and physicists.

I know it may be far fetched so no strong preference for sure.

Yours,
Linus Walleij
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