[PATCH 3/3] clk: Provide OF helper to mark clocks as CRITICAL

Hi Maxime,

On 01/02/16 06:32, Maxime Ripard wrote:

Hi Andre,

On Wed, Jan 27, 2016 at 11:51:45PM +0000, Andr? Przywara wrote:

quoted

Hi,

On 18/01/16 14:28, Lee Jones wrote:

quoted

This call matches clocks which have been marked as critical in DT
and sets the appropriate flag.  These flags can then be used to
mark the clock core flags appropriately prior to registration.

I like the idea of having a generic property very much. Also this solves
a problem I have in a very elegant way.

Not really. It has a significant set of drawbacks that we already
detailed in the initial thread, which are mostly related to the fact
that the clocks are to be left on is something that totally depends on
the software support in the kernel. Some clocks should be reported as
critical because they are simply missing a driver for it, some should
be because the driver for it as not been compiled, some should because
we don't have the proper clocks drivers yet for one of their
downstream clocks.

Basically, it all boils down to this: some clocks should never ever be
shutdown because <hardware reason>, and I believe it's the case Lee is
in. But most of the current code that would use it might, and might
even need at some point to shut down such a clock.

I was bascically interested in pushing the critical-clock property into
DT to solve that cumbersome clk-sunxi init scheme - which you have fixed
now in a much better way (thanks for that, btw.)
For that particular case the CPU clock really looks like being actually
critical in the hardware sense - no-one maybe except the mgmt core
should turn the one single CPU clock source off.

So I wonder if we should document this "for hardware reasons only" and
still have that property in DT?
At the weekend I coded something into the generic DT clock code to let
it parse for basically every clock node - without a particular driver
needing to ask for it.
If this sounds useful to you I can post that one.

Cheers,
Andre.

Mike's solution with the flags + handover was solving all this, I'm
not sure why he's not pushed it forward.

Maxime