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

From: Rob Herring <robh@kernel.org>
To: Max Krummenacher <max.oss.09@gmail.com>
Cc: max.krummenacher@toradex.com,
	Ulf Hansson <ulf.hansson@linaro.org>,
	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>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 0/5] power: domain: Add driver for a PM domain provider which controls
Date: Mon, 13 Jun 2022 13:15:49 -0600	[thread overview]
Message-ID: <20220613191549.GA4092455-robh@kernel.org> (raw)
In-Reply-To: <20220609150851.23084-1-max.oss.09@gmail.com>

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...

> This series adds a PM domain provider driver which enables/disables
> a regulator to control its power state. Additionally, marked with RFC,
> it adds two commits which actually make use of the new driver to
> instantiate a power domain provider and have a number of power
> domain consumers use the power domain.
> 
> The perceived use case is to control a common power domain used by
> several devices for which not all device drivers nessesarily have
> a means to control a regulator.

Why wouldn't they have means?

> It also handles the suspend / resume use case for such devices,
> the generic power domain framework will disable the domain once the
> last device has been suspend and will enable it again before resuming
> the first device.
> The generic power domain code handles a power domain consumer
> generically outside of the driver's code. (assuming the 'power-domains'
> property references exactly one power domain).

That's Linux implementation details.

> This allows to use the "regulator-pm-pd" driver with an arbitrary
> device just by adding the 'power-domains' property to the devices
> device tree node. However the device's dt-bindings schema likely does
> not allow the property 'power-domains'.
> One way to solve this would be to allow 'power-domains' globally
> similarly how 'status' and other common properties are allowed as
> implicit properties.

No. For 'power-domains' bindings have to define how many there are and 
what each one is.

Rob