[PATCH] ARM: cpu: Document and tweak clock-frequency property

On 8 December 2013 21:50, Mark Brown [off-list ref] wrote:

On Sun, Dec 08, 2013 at 07:51:59PM +0000, Peter Maydell wrote:

quoted

On 8 December 2013 19:22, Mark Brown [off-list ref] wrote:

quoted

(and doesn't reflect the actual deployed code reading the binding
which does use this property without documentation outside ePAPR and does
warn if it's absent)

quoted

This code should be fixed, then... (I'm pretty sure the kernel
has not always warned about the absence of this property,
or there would not be such a wide prevalence of DTs and
DT generating code which omitted it.)

Too late for that, it's shipping in stable kernels.

There does come a point where it's just nitpicking and not helpful but
if it has a substantial effect on functionality then it's useful.  In
this case suppressing the warning for non-asymmetric systems might be
sensible.

Hmm, so "mandatory for non-symmetric [I assume you mean
that and not really 'non-asymmetric'?], otherwise optional" ?
I think that would be reasonable and preserve backwards
compatibility.

For all practical purposes it is currently optional but the spec says
it is mandatory.  I would rather err on the side of not changing the
documentation in case someone does work based on ePAPR and/or an old
kernel and since doing that keeps the spec more stable even if we do
implement in a more tolerant fashion within Linux (as we should).

As I say, I don't think your specification currently does say
it is mandatory. If the documentation doesn't clearly list
it as a mandatory parameter, and a large number of
people writing DTS files or DT generation code haven't
put it in, and the kernel didn't complain about it not being
present for a long long time, then de facto it is optional,
and you should make your documentation conform with reality
and fix bugs where the kernel isn't coping with that.

thanks
-- PMM