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

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Message-ID: <3d3117d2-b3eb-1174-7061-b899cdcdf6ce@linaro.org>
Date:   Thu, 16 Mar 2023 00:50:49 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Bjorn Andersson <andersson@...nel.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 16.03.2023 00:00, Bjorn Andersson wrote:
> 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.
TBF we could, think:

sm1234_rpmpds[] = {
	[CX] = &foobar1,
	[CX_AO] = &foobar1_ao,

	[...]

	/* Legacy DT bindings */
	[SM1234_CX] = &foobar1,
	[SM1234_CX_AO] = &foobar1_ao,
};

WDYT?

Konrad
> 
> 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
>>>>>