linux-kernel - Re: [PATCH v2 1/2] dt-bindings: arm,scmi: Do not use clocks for SCMI performance domains

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Message-ID: <20201023135904.ayqznoxocxsvwl6v@bogus>
Date:   Fri, 23 Oct 2020 14:59:04 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, Sudeep Holla <sudeep.holla@....com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: Re: [PATCH v2 1/2] dt-bindings: arm,scmi: Do not use clocks for SCMI
 performance domains

On Fri, Oct 23, 2020 at 08:24:06AM -0500, Rob Herring wrote:
> On Thu, Oct 22, 2020 at 1:22 PM Sudeep Holla <sudeep.holla@....com> wrote:
> >
> > On Wed, Oct 21, 2020 at 07:31:03PM +0100, Sudeep Holla wrote:
> > > Commit dd461cd9183f ("opp: Allow dev_pm_opp_get_opp_table() to return
> > > -EPROBE_DEFER") handles -EPROBE_DEFER for the clock/interconnects within
> > > _allocate_opp_table() which is called from dev_pm_opp_add and it
> > > now propagates the error back to the caller.
> > >
> > > SCMI performance domain re-used clock bindings to keep it simple. However
> > > with the above mentioned change, if clock property is present in a device
> > > node, opps can't be added until clk_get succeeds. So in order to fix the
> > > issue, we can register dummy clocks which is completely ugly.
> > >
> > > Since there are no upstream users for the SCMI performance domain clock
> > > bindings, let us introduce separate performance domain bindings for the
> > > same.
> > >
> > > Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> > > ---
> > >  .../devicetree/bindings/arm/arm,scmi.txt      | 19 ++++++++++++++++---
> > >  1 file changed, 16 insertions(+), 3 deletions(-)
> > >
> > > v1[1]->v2:
> > >       - Changed the generic #perf-domain-cells to more SCMI specific
> > >         property #arm,scmi-perf-domain-cells
> > >
> >
> > Is more specific #arm,scmi-perf-domain-cells acceptable ?
> > Sorry for the rush, but this fixes SCMI cpufreq which is broken after
> > commit dd461cd9183f ("opp: Allow dev_pm_opp_get_opp_table() to return
> > -EPROBE_DEFER")
> 
> If you are in a rush, you'd better go the dummy clock route. We should
> get this binding right and I think that means something common, not
> SCMI specific.
> 

Ah OK, I assumed you wanted to make it SCMI specific. It makes sense to
have something generic like clocks for OPP domains.

There was discussion on the other thread to use empty OPP list for
firmware discoverable OPP list. Random thought here is to add domain ID
to OPP binding and use that ?

--
Regards,
Sudeep