On Sun, Oct 4, 2009 at 11:36 PM, Alexey Starikovskiy
<astarikovskiy@xxxxxxx> wrote:
> Hi Rafael,
>
> This is not my rule, it was/is the rule of power device class. If you do not
> agree to it, please change
> appropriate documentation.
Oh, I did not know that. Thank you for pointing it out. I think you
are refering to:
158Q: Suppose, my battery monitoring chip/firmware does not provides capacity
159 in percents, but provides charge_{now,full,empty}. Should I calculate
160 percentage capacity manually, inside the driver, and register CAPACITY
161 attribute? The same question about time_to_empty/time_to_full.
162A: Most likely, no. This class is designed to export properties which are
163 directly measurable by the specific hardware available.
164
165 Inferring not available properties using some heuristics or mathematical
166 model is not subject of work for a battery driver. Such functionality
167 should be factored out, and in fact, apm_power, the driver to serve
168 legacy APM API on top of power supply class, uses a simple heuristic of
169 approximating remaining battery capacity based on its charge, current,
170 voltage and so on. But full-fledged battery model is likely not subject
171 for kernel at all, as it would require floating point calculation to deal
172 with things like differential equations and Kalman filters. This is
173 better be handled by batteryd/libbattery, yet to be written.
We are not calculating anything new just by the pleasure of doing it,
we are correcting a wrong value provided by the hardware.
Please correct me if I misunderstood you.
>
> Regards,
> Alex.
>
> Rafael J. Wysocki пишет:
>>
>> On Sunday 04 October 2009, Alexey Starikovskiy wrote:
>>>
>>> Hi Miguel,
>>
>> Hi Alex,
>>
>>> I am going to reject your patch on the basis, that the battery driver
>>> should report only
>>> information it gained from battery hardware, not interpret it in any way.
>>> As your patch fall into "interpret" category, it does not belong in the
>>> kernel and battery
>>> driver in particular. You may suggest it to any/all user space battery
>>> monitoring applications,
>>> this is the place for "interpretations".
>>
>> Well, we do quirks for PCI devices, suspend quirks etc. in the kernel, so
>> I'm
>> not really sure we should use the "no interpretation" as a general rule.
>> IMO,
>> if there's a known broken system needing a quirk, it may just be more
>> reasonable to put the quirk into the kernel than to put it into every
>> single
>> user application out there.
>>
>> In this particular case we have an evidently quirky hardware (or BIOS) and
>> it's
>> not a fundamentally wrong idea to try to address that problem in the
>> kernel.
>>
>> Thanks,
>> Rafael
>
>
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