[PATCH 2/3] plat-nomadik: Added suspend/resume support for MTU timer.

[Linus Walleij]

2010/9/3 Alessandro Rubini <rubini-list at gnudd.com>:
> [Me]
>> Alessandro why do we kick in a prescaler if rate > (16 << 20)?
>> Seems weird to me too when I look at it, more like it'd be
>> if rate (1 << 20) which makes sense, if the counter will flip
>> around 20 bits in 1 second we prescale it by 16.
>
> Your "makes sense" is as subjective as mine. But on 8815, with 2.4MHz
> we overflow in around 1790 seconds. I feel it reasonable. If you
> prescale we get at 150kHz, which is 6.6 usec per tick: I don't like
> that figure too much.

Ah I got it backwards, actually I was thinking along the lines
that since (16 << 20) == (1 << 25) the latter would be more
apropriate thats what I think makes sense, it's so binary...
not (1 << 20) sorry for that.

So (1 << 25) means if bit 25 will switch in one second then
the remaining 7 bits will count less than 127 seconds
so roughly 2 minutes sleep (nice).

On a side note I believe we should then set the minimum range
for mul+div definied at the top of the file to something similar,
like 128.

I'll leave it to Jonas to come up with the best figure(s)!

Yours,
Linus Walleij