On 26 May 2014 18:41, Lucas Stach [off-list ref] wrote:

Just to mention that I am trying to help you and am not opposing any
change. We can add this field if its really required and I am just trying
to understand your problem and if we can solve it with current code.

No, setting voltage-tolerance to zero means I don't accept any tolerance
at all. Though in practice I have a variable tolerance as I just have a
fixed maximum voltage for the chip.

For example the i.MX53 has a fixed maximum voltage of 1.4V on the cpu
rail, so for the slowest OPP the acceptable voltage range is 0.8V to
1.4V, for the fastest OPP the range is 1.3V to 1.4V.

So if someone connects a fixed 1.3V regulator, I want to still be able
to use all OPPs, even though the slowest OPP wants 0.8V ideally. If I
were to use a tolerance I would have to set is to some relatively strict
value, in order to not exceed the maximum voltage at the highest OPP,
but this would mean I could not use the slowest OPP because it's out of
the tolerance range.

I understood the problem now. But I feel there is nothing imx specific here.
It should be a general concern and I want to know how are people
working around it currently.

IOW can we say that you want tolerance to work only on the positive
side? But no tolerance on the -ve side ?

Also, your example dts says that you do have different voltage levels
for each frequency but actually the regulator may only support a
single voltage. i.e. 1.4 volts.

--
viresh