linux-kernel - Re: [PATCH v1 0/5] power: domain: Add driver for a PM domain provider which controls

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Message-ID: <12e3bb72-af2d-653f-b342-c6b4d6a1f292@linaro.org>
Date:   Wed, 15 Jun 2022 10:15:15 -0700
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Max Krummenacher <max.oss.09@...il.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Rob Herring <robh@...nel.org>,
        Max Krummenacher <max.krummenacher@...adex.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        Francesco Dolcini <francesco.dolcini@...adex.com>,
        Mark Brown <broonie@...nel.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Andrejs Cainikovs <andrejs.cainikovs@...adex.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Fabio Estevam <festevam@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>, Vinod Koul <vkoul@...nel.org>,
        Will Deacon <will@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 0/5] power: domain: Add driver for a PM domain provider
 which controls

On 15/06/2022 09:10, Max Krummenacher wrote:
> Hi
> 
> On Tue, Jun 14, 2022 at 9:22 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>>
>> Hi Rob,
>>
>> On Mon, Jun 13, 2022 at 9:15 PM Rob Herring <robh@...nel.org> wrote:
>>> On Thu, Jun 09, 2022 at 05:08:46PM +0200, Max Krummenacher wrote:
>>>> From: Max Krummenacher <max.krummenacher@...adex.com>
>>>>
>>>> its power enable by using a regulator.
>>>>
>>>> The currently implemented PM domain providers are all specific to
>>>> a particular system on chip.
>>>
>>> Yes, power domains tend to be specific to an SoC... 'power-domains' is
>>> supposed to be power islands in a chip. Linux 'PM domains' can be
>>> anything...
> 
> I don't see why such power islands should be restricted to a SoC. You can
> build the exact same idea on a PCB or even more modular designs.

In the SoC these power islands are more-or-less defined. These are real
regions gated by some control knob.

Calling few devices on a board "power domain" does not make it a power
domain. There is no grouping, there is no control knob.

Aren't you now re-implementing regulator supplies? How is this different
than existing supplies?

Best regards,
Krzysztof