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 CFC9F182DD for ; Wed, 3 Jan 2024 09:47:59 +0000 (UTC) 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 62A10C15; Wed, 3 Jan 2024 01:48:39 -0800 (PST) Received: from bogus (unknown [10.57.74.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9649A3F7A6; Wed, 3 Jan 2024 01:47:50 -0800 (PST) Date: Wed, 3 Jan 2024 09:44:42 +0000 From: Sudeep Holla To: Konrad Dybcio Cc: Mark Rutland , Lorenzo Pieralisi , Sudeep Holla , Marijn Suijten , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Bjorn Andersson Subject: Re: [PATCH 2/2] firmware/psci: Set pm_set_resume/suspend_via_firmware() on qcom Message-ID: <20240103094442.mlh2pf3odof3ze3s@bogus> References: <20231227-topic-psci_fw_sus-v1-0-6910add70bf3@linaro.org> <20231227-topic-psci_fw_sus-v1-2-6910add70bf3@linaro.org> <20231228102801.fzaubcjq5thfwgxg@bogus> <20231228115053.zlypgc5uxxvghi4a@bogus> <376d3040-b9ed-4574-90d7-fb864d694e3c@linaro.org> <20231228124348.mmtceqeuean7ly6y@bogus> <7e31d489-de96-42f0-a72a-a581859e7131@linaro.org> 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: <7e31d489-de96-42f0-a72a-a581859e7131@linaro.org> On Tue, Jan 02, 2024 at 07:17:50PM +0100, Konrad Dybcio wrote: > On 28.12.2023 13:43, Sudeep Holla wrote: > > On Thu, Dec 28, 2023 at 01:16:28PM +0100, Konrad Dybcio wrote: > >> On 28.12.2023 12:50, Sudeep Holla wrote: > >>> On Thu, Dec 28, 2023 at 12:47:51PM +0100, Konrad Dybcio wrote: > >>>> On 28.12.2023 11:28, Sudeep Holla wrote: > >>>>> On Wed, Dec 27, 2023 at 11:15:31PM +0100, Konrad Dybcio wrote: > >>>>>> Most Qualcomm platforms implementing PSCI (ab)use CPU_SUSPEND for > >>>>>> entering various stages of suspend, across the SoC. These range from a > >>>>>> simple WFI to a full-fledged power collapse of the entire chip > >>>>>> (mostly, anyway). > >>>>>> > >>>>>> Some device drivers are curious to know whether "the firmware" (which is > >>>>>> often assumed to be ACPI) takes care of suspending or resuming the > >>>>>> platform. Set the flag that reports this behavior on the aforementioned > >>>>>> chips. > >>>>>> > >>>>>> Some newer Qualcomm chips ship with firmware that actually advertises > >>>>>> PSCI SYSTEM_SUSPEND, so the compatible list should only grow slightly. > >>>>>> > >>>>> > >>>>> NACK, just use suspend-to-idle if SYSTEM_SUSPEND is not advertised. It is > >>>>> designed for such platforms especially on x86/ACPI which don't advertise > >>>>> Sx states. I see no reason why that doesn't work on ARM platforms as well. > >>>> > >>>> Not sure if I got the message through well, but the bottom line is, on > >>>> Qualcomm platforms the "idle" states aren't actually just "idle" (read: > >>>> they're not like S0ix). All but the most shallow ones shut down quite a > >>>> chunk of the entire SoC, with the lowest ones being essentially S3 with > >>>> power being cut off from the entire chip, except for the memory rail. > >>>> > >>> > >>> No I understood that and S2I is exactly what you need. > >>> Have you checked if S2I already works as intended on these platforms ? > >> Yes, simple CPU idling works OOTB and the SoC power collapse only works > >> given the developer doesn't cut corners when bringing up the platform > >> (read: works on some of the ones we support, trying hard to expand that > >> group!) > >> > >>> What extra do you achieve with this hack by advertising fake S2R ? > >> Uh.. unless I misunderstood something, I'm not advertising s2ram.. > >> Quite the opposite, I'm making sure only s2idle is allowed. > >> > > > > Right, I didn't notice that in suspend_valid_all(), it can be rename > > suspend_valid_s2i or something. "All" indicates all state is valid. > > > > Anyways that is not the main point. IIUC S2I must still work if there is > > at-least one CPU idle state other than WFI without these changes. Right ? > > Yes, and it does > Thanks for the confirmation. > > > > If all these changes is to support S2I wih WFI only, then we can look at > > some generic solution as there were previous attempts to do something > > similar on other platforms IIRC. > > No, I'm just interested in setting the resume/suspend_via_firmware() > markers and the PSCI driver seems like a good place for it, be it on Agreed and your PATCH 1/2 does that exactly and hence I have acked it already. > all platforms with SYSTEM_SUSPEND and Qualcomm which sneaked equivalent > functionality into the CPU_SUSPEND call. > But I don't like the Qualcomm specific changes. -- Regards, Sudeep