From: Geert Uytterhoeven <geert@linux-m68k.org> To: Sudeep Holla <sudeep.holla@arm.com> Cc: Pavel Machek <pavel@ucw.cz>, Geert Uytterhoeven <geert+renesas@glider.be>, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Mark Rutland <mark.rutland@arm.com>, Lina Iyer <lina.iyer@linaro.org>, John Stultz <john.stultz@linaro.org>, Thomas Gleixner <tglx@linutronix.de>, "Rafael J . Wysocki" <rjw@rjwysocki.net>, Len Brown <len.brown@intel.com>, Rob Herring <robh+dt@kernel.org>, Magnus Damm <magnus.damm@gmail.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Linux-Renesas <linux-renesas-soc@vger.kernel.org>, Linux PM list <linux-pm@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode Date: Wed, 22 Feb 2017 14:47:39 +0100 [thread overview] Message-ID: <CAMuHMdU0fTtEXN9k477e3S-UUMNhd=U4_r0VOcyA1TGEgA5rmA@mail.gmail.com> (raw) In-Reply-To: <3caf0f3f-76e5-cb1e-7c0f-87ed5e1c2b86@arm.com> Hi Sudeep, On Tue, Feb 21, 2017 at 6:22 PM, Sudeep Holla <sudeep.holla@arm.com> wrote: > On 21/02/17 16:32, Geert Uytterhoeven wrote: >> On Tue, Feb 21, 2017 at 12:14 PM, Sudeep Holla <sudeep.holla@arm.com> wrote: >>> On 21/02/17 11:07, Pavel Machek wrote: >>>>> 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. >> >> How can Linux know if using "deep" suspend will allow to wake-up the system >> according to configured wake-up sources, or not? > > I am not sure if we have such selective configuration of wakeup source > implemented in Linux. > > ACPI specification has some provisions where each device can state if it > can specify device state in each system sleeping state that can wake the > system. > > DT has no mechanism today to express this relations. I had brought up > this discussion in plumbers(2015). Refer slide 7 in [0] > > And the way you are trying to do that is not correct IMO especially > making it just PSCI specific. > >> Note that "it will not, ever" is an accepted answer. > > IIUC, it's not implemented today. I can't talk about future ;), but your Good, so there's no need for the DT property, and drivers/firmware/psci.c should aways call do_cpu_idle() instead of PSCI SYSTEM_SUSPEND if any other wake-up sources are configured? That follows the principle of least surprise: it doesn't leave the user with a system that won't wake up the way he configured it to wake up. > proposal is horrible hack. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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From: geert@linux-m68k.org (Geert Uytterhoeven) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode Date: Wed, 22 Feb 2017 14:47:39 +0100 [thread overview] Message-ID: <CAMuHMdU0fTtEXN9k477e3S-UUMNhd=U4_r0VOcyA1TGEgA5rmA@mail.gmail.com> (raw) In-Reply-To: <3caf0f3f-76e5-cb1e-7c0f-87ed5e1c2b86@arm.com> Hi Sudeep, On Tue, Feb 21, 2017 at 6:22 PM, Sudeep Holla <sudeep.holla@arm.com> wrote: > On 21/02/17 16:32, Geert Uytterhoeven wrote: >> On Tue, Feb 21, 2017 at 12:14 PM, Sudeep Holla <sudeep.holla@arm.com> wrote: >>> On 21/02/17 11:07, Pavel Machek wrote: >>>>> 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. >> >> How can Linux know if using "deep" suspend will allow to wake-up the system >> according to configured wake-up sources, or not? > > I am not sure if we have such selective configuration of wakeup source > implemented in Linux. > > ACPI specification has some provisions where each device can state if it > can specify device state in each system sleeping state that can wake the > system. > > DT has no mechanism today to express this relations. I had brought up > this discussion in plumbers(2015). Refer slide 7 in [0] > > And the way you are trying to do that is not correct IMO especially > making it just PSCI specific. > >> Note that "it will not, ever" is an accepted answer. > > IIUC, it's not implemented today. I can't talk about future ;), but your Good, so there's no need for the DT property, and drivers/firmware/psci.c should aways call do_cpu_idle() instead of PSCI SYSTEM_SUSPEND if any other wake-up sources are configured? That follows the principle of least surprise: it doesn't leave the user with a system that won't wake up the way he configured it to wake up. > proposal is horrible hack. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
next prev parent reply other threads:[~2017-02-22 13:47 UTC|newest] Thread overview: 145+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-02-20 20:33 [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power Geert Uytterhoeven 2017-02-20 20:33 ` Geert Uytterhoeven 2017-02-20 20:33 ` [PATCH/RFC 1/6] alarmtimer: Postpone wake-up source registration until really available Geert Uytterhoeven 2017-02-20 20:33 ` Geert Uytterhoeven 2017-02-20 20:33 ` [PATCH/RFC 2/6] PM / Wakeup: Add wakeup_source_available() Geert Uytterhoeven 2017-02-20 20:33 ` Geert Uytterhoeven 2017-02-20 20:33 ` [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode Geert Uytterhoeven 2017-02-20 20:33 ` Geert Uytterhoeven 2017-02-21 10:42 ` Sudeep Holla 2017-02-21 10:42 ` Sudeep Holla 2017-02-21 16:23 ` Geert Uytterhoeven 2017-02-21 16:23 ` Geert Uytterhoeven 2017-02-21 16:23 ` Geert Uytterhoeven 2017-02-21 16:51 ` Sudeep Holla 2017-02-21 16:51 ` Sudeep Holla 2017-02-21 16:51 ` Sudeep Holla 2017-02-21 11:07 ` Pavel Machek 2017-02-21 11:07 ` Pavel Machek 2017-02-21 11:07 ` Pavel Machek 2017-02-21 11:14 ` Sudeep Holla 2017-02-21 11:14 ` Sudeep Holla 2017-02-21 11:14 ` Sudeep Holla 2017-02-21 16:32 ` Geert Uytterhoeven 2017-02-21 16:32 ` Geert Uytterhoeven 2017-02-21 16:32 ` Geert Uytterhoeven 2017-02-21 17:20 ` Mark Rutland 2017-02-21 17:20 ` Mark Rutland 2017-02-21 17:20 ` Mark Rutland 2017-02-21 17:20 ` Mark Rutland 2017-02-21 18:06 ` Geert Uytterhoeven 2017-02-21 18:06 ` Geert Uytterhoeven 2017-02-21 18:06 ` Geert Uytterhoeven 2017-02-21 18:06 ` Geert Uytterhoeven 2017-02-21 18:18 ` Mark Rutland 2017-02-21 18:18 ` Mark Rutland 2017-02-21 18:18 ` Mark Rutland 2017-02-21 18:23 ` Geert Uytterhoeven 2017-02-21 18:23 ` Geert Uytterhoeven 2017-02-21 18:23 ` Geert Uytterhoeven 2017-02-21 18:23 ` Geert Uytterhoeven 2017-02-21 17:22 ` Sudeep Holla 2017-02-21 17:22 ` Sudeep Holla 2017-02-21 17:22 ` Sudeep Holla 2017-02-21 17:22 ` Sudeep Holla 2017-02-22 13:47 ` Geert Uytterhoeven [this message] 2017-02-22 13:47 ` Geert Uytterhoeven 2017-02-22 13:47 ` Geert Uytterhoeven 2017-02-22 14:35 ` Sudeep Holla 2017-02-22 14:35 ` Sudeep Holla 2017-02-22 14:35 ` Sudeep Holla 2017-02-20 20:33 ` [PATCH/RFC 4/6] drivers: firmware: psci: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power Geert Uytterhoeven 2017-02-20 20:33 ` Geert Uytterhoeven 2017-02-21 10:50 ` Sudeep Holla 2017-02-21 10:50 ` Sudeep Holla 2017-02-21 16:36 ` Geert Uytterhoeven 2017-02-21 16:36 ` Geert Uytterhoeven 2017-02-21 16:36 ` Geert Uytterhoeven 2017-02-21 16:49 ` Sudeep Holla 2017-02-21 16:49 ` Sudeep Holla 2017-02-21 16:49 ` Sudeep Holla 2017-02-21 11:07 ` Pavel Machek 2017-02-21 11:07 ` Pavel Machek 2017-02-21 16:36 ` Geert Uytterhoeven 2017-02-21 16:36 ` Geert Uytterhoeven 2017-02-21 16:36 ` Geert Uytterhoeven 2017-02-21 17:54 ` Mark Rutland 2017-02-21 17:54 ` Mark Rutland 2017-02-21 17:48 ` Mark Rutland 2017-02-21 17:48 ` Mark Rutland 2017-02-22 14:05 ` Geert Uytterhoeven 2017-02-22 14:05 ` Geert Uytterhoeven 2017-02-22 14:05 ` Geert Uytterhoeven 2017-02-22 14:57 ` Rafael J. Wysocki 2017-02-22 14:57 ` Rafael J. Wysocki 2017-02-22 14:57 ` Rafael J. Wysocki 2017-02-22 14:57 ` Rafael J. Wysocki 2017-02-20 20:33 ` [PATCH/RFC 5/6] arm64: dts: r8a7795: Fix non-PMIC wake-up sources Geert Uytterhoeven 2017-02-20 20:33 ` Geert Uytterhoeven 2017-02-20 20:33 ` Geert Uytterhoeven 2017-02-20 20:33 ` [PATCH/RFC 6/6] arm64: dts: r8a7796: " Geert Uytterhoeven 2017-02-20 20:33 ` Geert Uytterhoeven 2017-02-21 10:38 ` [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power Sudeep Holla 2017-02-21 10:38 ` Sudeep Holla 2017-02-21 16:21 ` Geert Uytterhoeven 2017-02-21 16:21 ` Geert Uytterhoeven 2017-02-21 16:21 ` Geert Uytterhoeven 2017-02-21 16:45 ` Sudeep Holla 2017-02-21 16:45 ` Sudeep Holla 2017-02-21 16:45 ` Sudeep Holla 2017-02-21 16:45 ` Sudeep Holla 2017-02-21 17:34 ` Geert Uytterhoeven 2017-02-21 17:34 ` Geert Uytterhoeven 2017-02-21 17:34 ` Geert Uytterhoeven 2017-02-21 17:51 ` Sudeep Holla 2017-02-21 17:51 ` Sudeep Holla 2017-02-21 17:51 ` Sudeep Holla 2017-02-21 18:27 ` Sudeep Holla 2017-02-21 18:27 ` Sudeep Holla 2017-02-21 18:27 ` Sudeep Holla 2017-02-21 18:27 ` Sudeep Holla 2017-02-21 18:45 ` Sudeep Holla 2017-02-21 18:45 ` Sudeep Holla 2017-02-21 18:45 ` Sudeep Holla 2017-02-21 18:45 ` Sudeep Holla 2017-02-22 1:14 ` Rafael J. Wysocki 2017-02-22 1:14 ` Rafael J. Wysocki 2017-02-22 1:14 ` Rafael J. Wysocki 2017-02-22 11:03 ` Sudeep Holla 2017-02-22 11:03 ` Sudeep Holla 2017-02-22 11:03 ` Sudeep Holla 2017-02-22 13:38 ` Geert Uytterhoeven 2017-02-22 13:38 ` Geert Uytterhoeven 2017-02-22 13:38 ` Geert Uytterhoeven 2017-02-22 14:32 ` Sudeep Holla 2017-02-22 14:32 ` Sudeep Holla 2017-02-22 14:32 ` Sudeep Holla 2017-02-22 14:32 ` Sudeep Holla 2017-02-22 14:50 ` Rafael J. Wysocki 2017-02-22 14:50 ` Rafael J. Wysocki 2017-02-22 14:50 ` Rafael J. Wysocki 2017-02-22 14:50 ` Rafael J. Wysocki 2017-02-22 15:24 ` Sudeep Holla 2017-02-22 15:24 ` Sudeep Holla 2017-02-22 15:24 ` Sudeep Holla 2017-02-22 15:24 ` Sudeep Holla 2017-02-23 15:26 ` Geert Uytterhoeven 2017-02-23 15:26 ` Geert Uytterhoeven 2017-02-23 15:26 ` Geert Uytterhoeven 2017-02-23 15:34 ` Geert Uytterhoeven 2017-02-23 15:34 ` Geert Uytterhoeven 2017-02-23 15:34 ` Geert Uytterhoeven 2017-02-23 15:58 ` Sudeep Holla 2017-02-23 15:58 ` Sudeep Holla 2017-02-23 15:58 ` Sudeep Holla 2017-02-23 15:53 ` Sudeep Holla 2017-02-23 15:53 ` Sudeep Holla 2017-02-23 15:53 ` Sudeep Holla 2017-02-23 15:53 ` Sudeep Holla 2017-02-22 13:14 ` Geert Uytterhoeven 2017-02-22 13:14 ` Geert Uytterhoeven 2017-02-22 13:14 ` Geert Uytterhoeven 2017-02-22 14:31 ` Rafael J. Wysocki 2017-02-22 14:31 ` Rafael J. Wysocki 2017-02-22 14:31 ` Rafael J. Wysocki 2017-02-22 14:31 ` Rafael J. Wysocki
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