linux-kernel - Re: [PATCH v5 6/7] pmdomain: rockchip: add regulator support

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Message-ID: <3638293.eFTFzoEnKi@diego>
Date: Wed, 11 Dec 2024 15:54:09 +0100
From: Heiko Stübner <heiko@...ech.de>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Ulf Hansson <ulf.hansson@...aro.org>,
 Mark Brown <broonie@...nel.org>,
 Sebastian Reichel <sebastian.reichel@...labora.com>
Cc: Liam Girdwood <lgirdwood@...il.com>,
 Elaine Zhang <zhangqing@...k-chips.com>,
 Adrián Martínez Larumbe <adrian.larumbe@...labora.com>,
 Boris Brezillon <boris.brezillon@...labora.com>,
 Chen-Yu Tsai <wens@...e.org>, devicetree@...r.kernel.org,
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org,
 Sebastian Reichel <sebastian.reichel@...labora.com>, kernel@...labora.com
Subject: Re: [PATCH v5 6/7] pmdomain: rockchip: add regulator support

Am Mittwoch, 11. Dezember 2024, 15:26:51 CET schrieb Sebastian Reichel:
> Some power domains require extra voltages to be applied. For example
> trying to enable the GPU power domain on RK3588 fails when the SoC
> does not have VDD GPU enabled. The same is expected to happen for
> the NPU, which also has a dedicated supply line.
> 
> We get the regulator using devm_of_regulator_get(), so a missing
> dependency in the devicetree is handled gracefully by printing a warning
> and creating a dummy regulator. This is necessary, since existing DTs do
> not have the regulator described. They might still work if the regulator
> is marked as always-on. It is also working if the regulator is enabled
> at boot time and the GPU driver is probed before the kernel disables
> unused regulators.
> 
> The regulator itself is not acquired at driver probe time, since that
> creates an unsolvable circular dependency. The power domain driver must
> be probed early, since SoC peripherals need it. Regulators on the other
> hand depend on SoC peripherals like SPI, I2C or GPIO. MediaTek does not
> run into this, since they have two power domain drivers.
> 
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>

Reviewed-by: Heiko Stuebner <heiko@...ech.de>