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 E5A6279C6 for ; Thu, 28 Dec 2023 11:54:03 +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 2A2072F4; Thu, 28 Dec 2023 03:54:49 -0800 (PST) Received: from bogus (unknown [10.57.74.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 71CFC3F5A1; Thu, 28 Dec 2023 03:54:01 -0800 (PST) Date: Thu, 28 Dec 2023 11:50:53 +0000 From: Sudeep Holla To: Konrad Dybcio Cc: Mark Rutland , Sudeep Holla , Lorenzo Pieralisi , 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: <20231228115053.zlypgc5uxxvghi4a@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> 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: 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 ? What extra do you achieve with this hack by advertising fake S2R ? S2I will have less latency compared to S2R and the mem_sleep will be automatically set to S2I if S2R is not supported, so no userspace impact as well. So please let us know what this change provide extra over S2I ? Until then my NACK still stands. -- Regards, Sudeep