On Thu, Apr 28, 2011 at 3:43 PM, Colin Cross <ccross@xxxxxxxxxx> wrote:
> I understand the need for some sort of governor that can use device
> state to determine the necessary clock frequencies. ÂWhere I disagree
> is the connection to voltages. ÂThe governor should ONLY determine the
> frequencies desired, and the voltage required to meet those
> frequencies should be determined by the clock framework, based only on
> the clock and the frequency.
Yes, as long as AVS(Adaptive Voltage Scaling) is not involved, devfreq
does not need to care about voltages and let device driver (such as
the target callback or its callee) take care of voltages. Besides, my
impression on AVS is that AVS wouldn't be depending on software DVFS
scheme, at least with some AVS test on S5PC110. So, I'd say that it's
safe to let devfreq framework handle frequency only and let target
callback handle anything else except for choosing representative clock
frequency.
However, if we are going to detach devfreq from OPP, we only need to
provide frequency list at init and { an interface to control max/min
freq or an interface to lookup max/min freq of corresponding
representative clock. }
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ps. In our AVS test, the device drivers had nothing to do with voltage
scaling except for initializing devices. The H/W did everything about
voltage scaling dynamically.
Thanks,
MyungJoo.
--
MyungJoo Ham (íëì), Ph.D.
Mobile Software Platform Lab,
Digital Media and Communications (DMC) Business
Samsung Electronics
cell: 82-10-6714-2858
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