On Tue, Jul 31, 2012 at 07:32:20PM +0900, Alex Courbot wrote:

On 07/31/2012 07:45 AM, Stephen Warren wrote:

quoted

I wonder if using the same structure/array as input and output would
simplify the API; the platform data would fill in the fields mentioned
above, and power_seq_build() would parse those, then set other fields in
the same structs to the looked-up handle values?

The thing is that I am not sure what happens to the platform data
once probe() is done. Isn't it customary to mark it with __devinit
and have it freed after probing is successful?

No, platform data should stay around forever. Otherwise, consider what
would happen if your driver is built as a module and you unload and load
it again.

More generally, I think it is a good practice to have data
structures tailored right for what they need to do - code with
members that are meaningful only at given points of an instance's
life tends to be more confusing.

I agree. Furthermore the driver unload/reload would be another reason
not to reuse platform data as the output of the build() function.

But maybe what Stephen meant was more like filling a structure with data
taken from the platform data and pass that to a resolve() function which
would fill in the missing pieces like pointers to actual resources. I
imagine a managed interface would become a little trickier to do using
such an approach.

quoted

If the nodes have a unit address (i.e. end in "@n"), which they will
have to if all named "step" and there's more than one of them, then they
will need a matching reg property. Equally, the parent node will need
#address-cells and #size-cells too. So, the last couple lines would be:

	power-on-sequence {
		#address-cells = <1>;
		#size-cells = <0>;
		step@0 {
			reg = <0>;

That's precisely what I would like to avoid - I don't need the steps
to be numbered and I certainly have no use for a reg property. Isn't
there a way to make it simpler?

It's not technically valid to not have the reg property. Or
#address-cells and #size-cells properties for that matter.

Thierry