From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudeep Holla Subject: Re: [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode Date: Tue, 21 Feb 2017 11:14:16 +0000 Message-ID: References: <1487622809-25127-1-git-send-email-geert+renesas@glider.be> <1487622809-25127-4-git-send-email-geert+renesas@glider.be> <20170221110712.GB5021@amd> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170221110712.GB5021@amd> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Pavel Machek , Geert Uytterhoeven Cc: Sudeep Holla , Lorenzo Pieralisi , Mark Rutland , Lina Iyer , John Stultz , Thomas Gleixner , "Rafael J . Wysocki" , Len Brown , Rob Herring , Magnus Damm , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-renesas-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html