[PATCH] ARM: shmobile: compile drivers/sh for CONFIG_ARCH_SHMOBILE_MULTI

[laurent.pinchart@ideasonboard.com (Laurent Pinchart)]

Hi Geert,

On Tuesday 11 March 2014 20:15:04 Geert Uytterhoeven wrote:
> On Mon, Jan 20, 2014 at 11:52 PM, Laurent Pinchart wrote:
> > On Monday 20 January 2014 15:56:43 Mark Brown wrote:
> >> On Mon, Jan 20, 2014 at 04:48:10PM +0100, Laurent Pinchart wrote:
> >> > The problem isn't as simple as it seems, and more advanced
> >> > implementations that would allow listing clocks that should be managed
> >> > automatically (or the other way around) would also add another level of
> >> > complexity. The required information is platform-dependent, but we
> >> > currently don't express it as such in DT.
> >> 
> >> Well, the set of clocks an IP requires will tend to be the same - it's
> >> normally just that integrators may have done things like tie them
> >> together or decide to spread confusion by renaming them.
> > 
> > That's the problem :-) How should the runtime PM core be given the list of
> > clocks it needs to manage ? That information needs to come from somewhere.
> 
> Stirring the pot again...
> 
> Which clocks a device needs is expressed in DT with CCF.
> In the simple case, the runtime PM core can just control them based on
> device use.
> In the complex case, the driver can regain control using its own pm
> callbacks, right?

Sure, the driver can of course control the clocks manually in its PM callbacks 
if it needs to. The point, however, is to control the clocks from core code 
whenever possible. We thus need to define exact semantics to make sure each 
side knows what tasks to perform, and what to expect from the other side. For 
instance, in the DT case, the runtime PM core can easily get the list of the 
clocks used by the device from its DT node, but how can it know which clock(s) 
it should manage automatically and which clock(s) it should leave for the 
driver to control ?

> Probably I'm still missing something, as I haven't had enough exposure to
> runtime PM and CCF ;-)

-- 
Regards,

Laurent Pinchart