From mboxrd@z Thu Jan 1 00:00:00 1970 From: sudeep.holla@arm.com (Sudeep Holla) Date: Tue, 21 Feb 2017 11:14:16 +0000 Subject: [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode In-Reply-To: <20170221110712.GB5021@amd> References: <1487622809-25127-1-git-send-email-geert+renesas@glider.be> <1487622809-25127-4-git-send-email-geert+renesas@glider.be> <20170221110712.GB5021@amd> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 21/02/17 11:07, Pavel Machek wrote: > Hi! > >> Enable support for "shallow" suspend mode, also known as "Standby" or >> "Power-On Suspend". >> >> As secondary CPU cores are taken offline, "shallow" suspend mode saves >> slightly more power than "s2idle", but less than "deep" suspend mode. >> However, unlike "deep" suspend mode, "shallow" suspend mode can be used >> regardless of the presence of support for PSCI_SYSTEM_SUSPEND, which is >> an optional API in PSCI v1.0. > > If system supports "shallow" suspend, why does not PSCI implement it? > Yes it can, and IIUC it already does on this platform with CPU_SUSPEND. All it now needs is just to use existing "freeze" suspend mode in Linux. > In the past, I was told PSCI will not turn into ACPI-like mess, and > that we'll be able to fix PSCI and will not have to work around its > problems in kernel :-(. Can you be more elaborate on the mess you see on this Renesas platform. For me, it looks like this patch is attempting to *re-implement* the existing "suspend-to-idle" functionality. So IMO, this patch set is creating unnecessary mess giving an illusion that PSCI specification is broken. -- Regards, Sudeep