linux-kernel - Re: [PATCH 3/3] arm64: dts: qcom: Split out SA8155P and use correct RPMh power domains

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Message-ID: <20230315230024.wxuqthay74i5zgrq@ripper>
Date:   Wed, 15 Mar 2023 16:00:24 -0700
From:   Bjorn Andersson <andersson@...nel.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     linux-arm-msm@...r.kernel.org, agross@...nel.org,
        krzysztof.kozlowski@...aro.org, marijn.suijten@...ainline.org,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] arm64: dts: qcom: Split out SA8155P and use correct
 RPMh power domains

On Tue, Mar 14, 2023 at 12:41:45PM +0100, Konrad Dybcio wrote:
> 
> 
> On 14.03.2023 12:36, Konrad Dybcio wrote:
> > 
> > 
> > On 14.03.2023 01:10, Bjorn Andersson wrote:
> >> On Tue, Feb 14, 2023 at 10:54:35AM +0100, Konrad Dybcio wrote:
> >>> The RPMhPD setup on SA8155P is different compared to SM8150. Correct
> >>> it to ensure the platform will not try accessing forbidden/missing
> >>> RPMh entries at boot, as a bad vote will hang the machine.
> >>>
> >>
> >> I don't see that this will scale, as soon as someone adds a new device
> >> in sm8150.dtsi that has the need to scale a power rail this will be
> >> forgotten and we will have a mix of references to the SM8150 and SA8155P
> >> value space.
> >>
> >> That said, I think it's reasonable to avoid duplicating the entire
> >> sm8150.dtsi.
> > Yeah, this problem has no obvious good solutions and even though it's
> > not very elegant, this seems to be the less bad one..
> > 
> >>
> >> How about making the SA8155P_* macros match the SM8150_* macros?
> >> That way things will fail gracefully if a device node references a
> >> resource not defined for either platform...
> > Okay, let's do that
> Re-thinking it, it's good that the indices don't match, as this way the
> board will (should) refuse to function properly if there's an oversight,
> which may have gone unnoticed if they were matching, so this only guards
> us against programmer error which is not great :/
> 

Right, ensuring that the resource indices never collides would be a good
way to capture this issue, as well as copy-paste errors etc. My
pragmatic proposal is that we make SA8155P_x == SM8150_x where a match
exist, and for the ones that doesn't match we pick numbers that doesn't
collide between the platforms.

The alternative is to start SA8155P_x at 11, but it's different and
forces sa8155p.dtsi to redefine every single power-domains property...


This does bring back the feeling that it was a mistake to include the
platform name in these defines in the first place... Not sure if it's
worth mixing generic defines into the picture at this point, given that
we I don't see a way to use them on any existing platform.

Regards,
Bjorn

> Konrad
> > 
> > Konrad
> >>
> >> Regards,
> >> Bjorn
> >>
> >>> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> >>> ---
> >>>  arch/arm64/boot/dts/qcom/sa8155p-adp.dts |  2 +-
> >>>  arch/arm64/boot/dts/qcom/sa8155p.dtsi    | 51 ++++++++++++++++++++++++
> >>>  2 files changed, 52 insertions(+), 1 deletion(-)
> >>>  create mode 100644 arch/arm64/boot/dts/qcom/sa8155p.dtsi
> >>>
> >>> diff --git a/arch/arm64/boot/dts/qcom/sa8155p-adp.dts b/arch/arm64/boot/dts/qcom/sa8155p-adp.dts
> >>> index 459384ec8f23..9454e8e4e517 100644
> >>> --- a/arch/arm64/boot/dts/qcom/sa8155p-adp.dts
> >>> +++ b/arch/arm64/boot/dts/qcom/sa8155p-adp.dts
> >>> @@ -7,7 +7,7 @@
> >>>  
> >>>  #include <dt-bindings/regulator/qcom,rpmh-regulator.h>
> >>>  #include <dt-bindings/gpio/gpio.h>
> >>> -#include "sm8150.dtsi"
> >>> +#include "sa8155p.dtsi"
> >>>  #include "pmm8155au_1.dtsi"
> >>>  #include "pmm8155au_2.dtsi"
> >>>  
> >>> diff --git a/arch/arm64/boot/dts/qcom/sa8155p.dtsi b/arch/arm64/boot/dts/qcom/sa8155p.dtsi
> >>> new file mode 100644
> >>> index 000000000000..f2fd7c28764e
> >>> --- /dev/null
> >>> +++ b/arch/arm64/boot/dts/qcom/sa8155p.dtsi
> >>> @@ -0,0 +1,51 @@
> >>> +// SPDX-License-Identifier: BSD-3-Clause
> >>> +/*
> >>> + * Copyright (c) 2023, Linaro Limited
> >>> + *
> >>> + * SA8155P is an automotive variant of SM8150, with some minor changes.
> >>> + * Most notably, the RPMhPD setup differs: MMCX and LCX/LMX rails are gone.
> >>> + */
> >>> +
> >>> +#include "sm8150.dtsi"
> >>> +
> >>> +&dispcc {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>;
> >>> +};
> >>> +
> >>> +&mdss_mdp {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>;
> >>> +};
> >>> +
> >>> +&mdss_dsi0 {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>;
> >>> +};
> >>> +
> >>> +&mdss_dsi1 {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>;
> >>> +};
> >>> +
> >>> +&remoteproc_adsp {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>;
> >>> +};
> >>> +
> >>> +&remoteproc_cdsp {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>;
> >>> +};
> >>> +
> >>> +&remoteproc_mpss {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>,
> >>> +			<&rpmhpd SA8155P_MSS>;
> >>> +};
> >>> +
> >>> +&remoteproc_slpi {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>,
> >>> +			<&rpmhpd SA8155P_MX>;
> >>> +};
> >>> +
> >>> +&rpmhpd {
> >>> +	compatible = "qcom,sa8155p-rpmhpd";
> >>> +};
> >>> +
> >>> +&sdhc_2 {
> >>> +	power-domains = <&rpmhpd SA8155P_CX>;
> >>> +};
> >>> -- 
> >>> 2.39.1
> >>>