linux-kernel - Re: [PATCH 1/5] riscv: dts: allwinner: Update opp table to allow CPU frequency scaling

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Date: Fri, 15 Dec 2023 16:18:35 +0100
From: Brandon Cheo Fusi <fusibrandon13@...il.com>
To: jernej.skrabec@...il.com
Cc: aou@...s.berkeley.edu,
	conor+dt@...nel.org,
	conor@...nel.org,
	devicetree@...r.kernel.org,
	fusibrandon13@...il.com,
	krzysztof.kozlowski+dt@...aro.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-sunxi@...ts.linux.dev,
	palmer@...belt.com,
	paul.walmsley@...ive.com,
	rafael@...nel.org,
	robh+dt@...nel.org,
	samuel@...lland.org,
	tiny.windzz@...il.com,
	viresh.kumar@...aro.org,
	wens@...e.org
Subject: Re: [PATCH 1/5] riscv: dts: allwinner: Update opp table to allow CPU frequency scaling

On Thu, Dec 14, 2023 at 5:37 PM Jernej Škrabec <jernej.skrabec@...il.com> wrote:
>
> On Thursday, December 14, 2023 2:47:14 PM CET Conor Dooley wrote:
> > On Thu, Dec 14, 2023 at 04:44:46PM +0530, Viresh Kumar wrote:
> > > On 14-12-23, 11:33, Brandon Cheo Fusi wrote:
> > > > Two OPPs are currently defined for the D1/D1s; one at 408MHz and
> > > > another at 1.08GHz. Switching between these can be done with the
> > > > "sun50i-cpufreq-nvmem" driver. This patch populates the opp table
> > > > appropriately, with inspiration from
> > > > https://github.com/Tina-Linux/linux-5.4/blob/master/arch/riscv/boot/dts/sunxi/sun20iw1p1.dtsi
> > > >
> > > > The supply voltages are PWM-controlled, but support for that IP
> > > > is still in the works. So stick to a fixed 0.9V vdd-cpu supply,
> > > > which seems to be the default on most D1 boards.
> > > >
> > > > Signed-off-by: Brandon Cheo Fusi <fusibrandon13@...il.com>
> > > > ---
> > > >  arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi | 18 +++++++++++++++---
> > > >  1 file changed, 15 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi b/arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi
> > > > index 64c3c2e6c..e211fe4c7 100644
> > > > --- a/arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi
> > > > +++ b/arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi
> > > > @@ -39,16 +39,22 @@ cpu0_intc: interrupt-controller {
> > > >   };
> > > >
> > > >   opp_table_cpu: opp-table-cpu {
> > > > -         compatible = "operating-points-v2";
> > > > +         compatible = "allwinner,sun20i-d1-operating-points",
> > >
> > > I don't think you should add a new compatible for every SoC that needs
> > > to be supported by a DT bindings and cpufreq driver. Maybe you should
> > > just reuse "allwinner,sun50i-h6-operating-points" and it will work
> > > fine for you ?
> > >
> > > Rob ?
> >
> > The driver can definitely just reuse sun50i-h6, but the binding and
> > devicetree should have a soc-specific compatible for the sun20i-d1.
>
> Correct. This is to avoid later regrets if it turns out there are some slight
> differences or additional functionality.
>
> Best regards,
> Jernej
>
> >
> > That said, the compatible does need to be documented, there's a
> > dt-bindings patch missing from this series.
> >
> > Cheers,
> > Conor.
>
>
>
>

This dt-bindings patch will be available in v2

Thanks for reviewing.
Brandon.