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

From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
To: Max Krummenacher <max.oss.09@gmail.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Rob Herring <robh@kernel.org>,
	Max Krummenacher <max.krummenacher@toradex.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Linux PM list <linux-pm@vger.kernel.org>,
	Francesco Dolcini <francesco.dolcini@toradex.com>,
	Mark Brown <broonie@kernel.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Kevin Hilman <khilman@kernel.org>,
	Andrejs Cainikovs <andrejs.cainikovs@toradex.com>,
	Biju Das <biju.das.jz@bp.renesas.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	Fabio Estevam <festevam@gmail.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Marcel Ziswiler <marcel.ziswiler@toradex.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Shawn Guo <shawnguo@kernel.org>, Vinod Koul <vkoul@kernel.org>,
	Will Deacon <will@kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 0/5] power: domain: Add driver for a PM domain provider which controls
Date: Wed, 15 Jun 2022 10:15:15 -0700	[thread overview]
Message-ID: <12e3bb72-af2d-653f-b342-c6b4d6a1f292@linaro.org> (raw)
In-Reply-To: <CAEHkU3VVM0zUsaKMUGeSzfbLmVJW6rqXGLv7TqaLTEQeXEVkUA@mail.gmail.com>

On 15/06/2022 09:10, Max Krummenacher wrote:
> Hi
> 
> On Tue, Jun 14, 2022 at 9:22 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>>
>> Hi Rob,
>>
>> On Mon, Jun 13, 2022 at 9:15 PM Rob Herring <robh@kernel.org> wrote:
>>> On Thu, Jun 09, 2022 at 05:08:46PM +0200, Max Krummenacher wrote:
>>>> From: Max Krummenacher <max.krummenacher@toradex.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