From mboxrd@z Thu Jan 1 00:00:00 1970 From: sudeep.holla@arm.com (Sudeep Holla) Date: Mon, 22 Aug 2016 16:00:46 +0100 Subject: how to enable suspend to ram for arm-64 bits In-Reply-To: References: <06a4f0d7-9022-578d-99e0-ddcde31ed895@arm.com> <82ddd0e1-9ecc-5e54-e8ee-86f947fc0ecd@arm.com> <62cbf1a0-268a-f9f5-09af-c155a8a77508@arm.com> Message-ID: <6fa7fdb7-7b8d-f955-75e6-75647a6d57a3@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 22/08/16 15:41, yoma sophian wrote: > hi Sudeep: > >>> Yes, I agree with you. >>> But it may not mean the ONLY way for all armv8 platform that support >>> suspend method is PSCI. >> >> I would say yes but if you have a real good reason not to adopt PSCI on >> your platform then you can try present that. It should be convincing >> enough to deviate from the standards :) > > Since we don't implement full features of PSCI on our platform, that > is why we wants to know whether there is registration of platform > suspend method. > For adding support for your platform in the mainline kernel, you need to support SYSTEM_SUSPEND in psci. There's no other way currently with the mainline. > BTW, from the git log, it seems psci.c doesn't register system suspend > until Linux 4.4. Correct. > if so, before 4.4, how aarch64 support such as str, echo mem > > /sys/power/state , suspend flow? > You can back-port those patches, they are quite trivial if you need it on pre-v4.4 kernel. Moreover, how do you plan to support system system without PSCI ? How will you let the higher exception softwares know that you are entering system suspend. How will their context resumed back ? -- Regards, Sudeep