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Date: Mon, 13 Jan 2025 10:31:21 +0000
From: Sudeep Holla <sudeep.holla@arm.com>
To: "Peng Fan (OSS)" <peng.fan@oss.nxp.com>
Cc: <cristian.marussi@arm.com>, <ulf.hansson@linaro.org>,
	Sudeep Holla <sudeep.holla@arm.com>, <arm-scmi@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>, <linux-pm@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <ranjani.vaidyanathan@nxp.com>,
	Peng Fan <peng.fan@nxp.com>
Subject: Re: [PATCH] pmdomain: arm: scmi_pm_domain: Initialize state as off
Message-ID: <Z4TreQ5bA9qiMTgC@bogus>
References: <20250110061346.2440772-1-peng.fan@oss.nxp.com>
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In-Reply-To: <20250110061346.2440772-1-peng.fan@oss.nxp.com>

On Fri, Jan 10, 2025 at 02:13:46PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
> 
> Per ARM SCMI Spec DEN0056E, page 16, "The platform may disable a resource
> if no agent has requested to use that resource."
>

True, but ...

> Linux Kernel should not rely on a state that it has not requested, so
> make state as off during initialization.
>

IIUC, this was done to avoid any transitions if the bootloader like U-Boot
has turned on the resource and OS can just rely on that stay. Anyways if
the resource is not used by any driver/device in the kernel, won't it be
turned off anyways ? What am I missing ?

I need to dig details, but I remember doing what this patch does and
reverting to what we have based on the feedback IIRC.

--
Regards,
Sudeep