Re: [PATCH V2 1/2] opp: Allow dev_pm_opp_get_opp_table() to return -EPROBE_DEFER

[Sudeep Holla]

On Tue, Oct 20, 2020 at 03:11:34PM +0530, Viresh Kumar wrote:
> On 20-10-20, 10:37, Sudeep Holla wrote:
> > On Tue, Oct 20, 2020 at 11:24:32AM +0530, Viresh Kumar wrote:
> > > On 20-10-20, 10:35, Viresh Kumar wrote:
> > > > On 19-10-20, 15:10, Sudeep Holla wrote:
> > > > > On Mon, Oct 19, 2020 at 04:05:35PM +0530, Viresh Kumar wrote:
> > > > > > On 19-10-20, 11:12, Sudeep Holla wrote:
> > > > > > > Yes it has clocks property but used by SCMI(for CPUFreq/DevFreq) and not
> > > > > > > by any clock provider driver. E.g. the issue you will see if "clocks"
> > > > > > > property is used instead of "qcom,freq-domain" on Qcom parts.
> > > > > > 
> > > > > > Okay, I understand. But what I still don't understand is why it fails
> > > > > > for you. You have a clocks property in DT for the CPU, the OPP core
> > > > > > tries to get it and will get deferred-probed, which will try probing
> > > > > > at a later point of time and it shall work then. Isn't it ?
> > > > > >
> > > > > 
> > > > > Nope unfortunately. We don't have clock provider, so clk_get will
> > > > > never succeed and always return -EPROBE_DEFER.
> > > > 
> > > > Now this is really bad, you have a fake clocks property, how is the
> > > > OPP core supposed to know it ? Damn.
> > > 
> > > What about instead of fixing the OPP core, which really is doing the
> > > right thing, we fix your driver (as you can't fix the DT) and add a
> > > dummy CPU clk to make it all work ?
> > >
> > 
> > I really would avoid that. I would rather change the binding as there is
> > no single official users of that binding in the upstream tree.
> 
> But how will you solve backward compatibility thing then ?
> 

I am just betting on the fact that no users upstream means no backward
compatibility needed. If someone raises issue we need to add backward
compatibility with dummy clk as you suggested.

-- 
Regards,
Sudeep