From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 533C31ABEB7; Fri, 20 Dec 2024 11:27:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734694031; cv=none; b=Kk43zsCHaCCD+0cAL4oZrq3CR4IIzfyYqqysMKPY9RCoS7baGd7N4BINAO8IOQKASnnkjD8cg9zz8nrkAtpiesfDYXmALtZMo6t4UeCiVHLd5DFYPpkfhfxJDHgtowWjCP7hpKY/TVhxJUbFdvqUWNF6wlOB8jvwszW7NkM+Igw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734694031; c=relaxed/simple; bh=z1DjV6lFG0FNp3hEITPnp85ERL6hxq0qTRKArvOILnk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GzWoafqvdAbRbd0IcQElzuJWbGwDjig8Tj1w8f6kKadXrA14PuQjeEo6DQp+VQ/ctqGMTRkll5+prjwYWEHlA3dRtloffkLfCCmpx2km5kl8d57WDn0pea0X0Vv/l49g21CLRC9LYuFajASL3mIhGLpoQt/ZH4aEFBDa1gwAUKk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CFB221480; Fri, 20 Dec 2024 03:27:36 -0800 (PST) Received: from bogus (e133711.arm.com [10.1.196.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D60593F58B; Fri, 20 Dec 2024 03:27:06 -0800 (PST) Date: Fri, 20 Dec 2024 11:27:04 +0000 From: Sudeep Holla To: Konrad Dybcio Cc: Konrad Dybcio , Rob Herring , Krzysztof Kozlowski , Sudeep Holla , Conor Dooley , Lorenzo Pieralisi , Mark Rutland , Marijn Suijten , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Bjorn Andersson Subject: Re: [PATCH 1/3] dt-bindings: arm,psci: Allow S2RAM power_state parameter description Message-ID: References: <20241028-topic-cpu_suspend_s2ram-v1-0-9fdd9a04b75c@oss.qualcomm.com> <20241028-topic-cpu_suspend_s2ram-v1-1-9fdd9a04b75c@oss.qualcomm.com> <54cc4221-ba5f-4741-9033-20874265ca01@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54cc4221-ba5f-4741-9033-20874265ca01@oss.qualcomm.com> On Thu, Dec 19, 2024 at 08:43:27PM +0100, Konrad Dybcio wrote: > On 6.12.2024 11:21 AM, Sudeep Holla wrote: > > On Mon, Oct 28, 2024 at 03:22:57PM +0100, Konrad Dybcio wrote: > >> From: Konrad Dybcio > >> > >> Certain firmware implementations (such as the ones found on Qualcomm > >> SoCs between roughly 2015 and 2023) expose an S3-like S2RAM state > >> through the CPU_SUSPEND call, as opposed to exposing PSCIv1.0's > >> optional PSCI_SYSTEM_SUSPEND. > >> > > > > If so, can you elaborate why s2idle doesn't work as an alternative to what > > you are hacking up here. > > Please see other branches of this thread > > > > >> This really doesn't work well with the model where we associate all > >> calls to CPU_SUSPEND with cpuidle. Allow specifying a single special > >> CPU_SUSPEND suspend parameter value that is to be treated just like > >> SYSTEM_SUSPEND from the OS's point of view. > >> > >> Signed-off-by: Konrad Dybcio > >> --- > >> Documentation/devicetree/bindings/arm/psci.yaml | 6 ++++++ > >> 1 file changed, 6 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml > >> index cbb012e217ab80c1ca88e611e7acc06c6d56fad0..a6901878697c8e1ec1cbfed62298ae3bc58f2501 100644 > >> --- a/Documentation/devicetree/bindings/arm/psci.yaml > >> +++ b/Documentation/devicetree/bindings/arm/psci.yaml > >> @@ -98,6 +98,12 @@ properties: > >> [1] Kernel documentation - ARM idle states bindings > >> Documentation/devicetree/bindings/cpu/idle-states.yaml > >> > >> + arm,psci-s2ram-param: > >> + $ref: /schemas/types.yaml#/definitions/uint32 > >> + description: > >> + power_state parameter denoting the S2RAM/S3-like system suspend state > > > > Yet another NACK as this corresponds to PSCI SYSTEM_SUSPEND and as per > > specification it takes no such parameter. This is just misleading. > > > > Yeah PSCI_SYSTEM_SUSPEND takes care of this on platforms that expose it. > And those that don't advertise/expose don't get to use, simple. > DEN0022F.b Section 6.5. recommends that CPU_SUSPEND StateID includes > a field for system-level power down states. This binding change only > adds a way for DT-based platforms to associate such state with S2RAM > suspend. > Sure, just use the CPU_SUSPEND bindings that already exist. No need to define this as some special case if it is exposed as CPU_SUSPEND idle state. Not sure why you want to do it differently. I understand the need to handle it different in the kernel, but I don't understand to define the new bindings for that. Just use the existing bindings for the idle states. Again I see no exception for this case. > That may be a bit Linux-specific whereas bindings are supposed to be > OS-agnostic, but since we effectively want one PSCI state for deep > suspend regardless of the OS, I would think this kind of hint is fine. > Exactly, that's the reason for not changing this into special case and special binding for that special case created. -- Regards, Sudeep