linux-kernel - Re: [PATCH 0/6] soc: samsung: pm

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Date:   Fri, 10 Mar 2023 15:41:08 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Sam Protsenko <semen.protsenko@...aro.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Chanho Park <chanho61.park@...sung.com>,
        David Virag <virag.david003@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/6] soc: samsung: pm_domains: Add Exynos850 support

On 09/03/2023 11:12, Marek Szyprowski wrote:
> Hi Sam,
> 
> On 09.03.2023 00:09, Sam Protsenko wrote:
>> Power Domains in Exynos850 are not really different from other Exynos
>> platforms. Enabling Exynos850 support in the PD driver is really just a
>> matter of adding:
>>
>>      static const struct exynos_pm_domain_config exynos850_cfg = {
>>          .local_pwr_cfg = 0x1,
>>      };
>>
>> to the driver. But in the face of recent developments, e.g. this patch:
>>
>>      arm64: dts: exynos: move MIPI phy to PMU node in Exynos5433
>>
>> it looked logical to rework the PD driver a bit to support its nesting
>> under the PMU node, while adding Exynos850 support to it. Initially I
>> only wanted to add syscon regmap support via some dedicated property,
>> but pulling PD nodes under the PMU syscon looks like more correct way.
> 
> Frankly speaking if you are changing this, you can go even further. 
> Simply make PMU node a PM domain provider and specify the power domain 
> as a phandle parameter. This is how it should have been done from the 
> beginning, but for some unknown reasons wasn't. There is really no need 
> to have a separate node for each power domain. This will also move 
> implementation details to the PMU / power domain drivers and it will 
> make it much easier to extend/modify it in the future. IMHO same applies 
> for PHY nodes.

I agree. The "samsung,pd-index" property is not a correct approach.
Either you use address space or not. If not, then this should be part of
power domain provider, which is also matching most of other SoC
architectures.


Best regards,
Krzysztof