From: Jon Hunter <jon-hunter@ti.com>
To: "Mark A. Greer" <mgreer@animalcreek.com>
Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
khilman@ti.com, paul@pwsan.com
Subject: Re: [PATCH 02/12] arm: omap3: Only sleep during cpu_idle if I/O wake-ups work
Date: Wed, 11 Apr 2012 18:42:44 -0500 [thread overview]
Message-ID: <4F8616F4.4010109@ti.com> (raw)
In-Reply-To: <1334171147-7517-3-git-send-email-mgreer@animalcreek.com>
Hi Mark,
On 04/11/2012 02:05 PM, Mark A. Greer wrote:
> From: "Mark A. Greer" <mgreer@animalcreek.com>
>
> Currently in the OMAP3 code, cpu_idle() calls pm_idle(),
> which is a function pointer set to omap3_pm_idle()).
> omap3_pm_idle() calls omap_sram_idle() which eventually
> causes a 'wfi' instruction to be executed effectively
> putting the system to sleep. It is assumed that an
> I/O wake-up event will occur to wake the system up again.
> This doesn't work on systems that don't support I/O wake-ups
> (indicated by omap3_has_io_wakeup() returning false).
>
> Leaving pm_idle() pointing to default_idle() won't work
> either because the cpu_<processor>_do_idle() routine which
> is eventually called may also execute a 'wfi' instruction
> (e.g., cpu_v7_do_idle()).
So with this change you will never execute wfi?
I would have thought a timer or peripheral interrupt would be able to
bring you out of wfi. IO wake-ups would only be needed for very low
power states. At least that is how it is on OMAP devices. I am not sure
how the AMxxx devices differ.
Cheers
Jon
WARNING: multiple messages have this Message-ID (diff)
From: jon-hunter@ti.com (Jon Hunter)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 02/12] arm: omap3: Only sleep during cpu_idle if I/O wake-ups work
Date: Wed, 11 Apr 2012 18:42:44 -0500 [thread overview]
Message-ID: <4F8616F4.4010109@ti.com> (raw)
In-Reply-To: <1334171147-7517-3-git-send-email-mgreer@animalcreek.com>
Hi Mark,
On 04/11/2012 02:05 PM, Mark A. Greer wrote:
> From: "Mark A. Greer" <mgreer@animalcreek.com>
>
> Currently in the OMAP3 code, cpu_idle() calls pm_idle(),
> which is a function pointer set to omap3_pm_idle()).
> omap3_pm_idle() calls omap_sram_idle() which eventually
> causes a 'wfi' instruction to be executed effectively
> putting the system to sleep. It is assumed that an
> I/O wake-up event will occur to wake the system up again.
> This doesn't work on systems that don't support I/O wake-ups
> (indicated by omap3_has_io_wakeup() returning false).
>
> Leaving pm_idle() pointing to default_idle() won't work
> either because the cpu_<processor>_do_idle() routine which
> is eventually called may also execute a 'wfi' instruction
> (e.g., cpu_v7_do_idle()).
So with this change you will never execute wfi?
I would have thought a timer or peripheral interrupt would be able to
bring you out of wfi. IO wake-ups would only be needed for very low
power states. At least that is how it is on OMAP devices. I am not sure
how the AMxxx devices differ.
Cheers
Jon
next prev parent reply other threads:[~2012-04-11 23:42 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-11 19:05 arm: omap3: am35x: Powerdomain, EMIF4, etc. fixups Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 01/12] arm: omap3: Only access IVA if one exists Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 02/12] arm: omap3: Only sleep during cpu_idle if I/O wake-ups work Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 21:38 ` Paul Walmsley
2012-04-11 21:38 ` Paul Walmsley
2012-04-11 23:42 ` Jon Hunter [this message]
2012-04-11 23:42 ` Jon Hunter
2012-04-13 0:13 ` Mark A. Greer
2012-04-13 0:13 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 03/12] arm: omap3: Only sleep in cpuidle driver " Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 21:37 ` Paul Walmsley
2012-04-11 21:37 ` Paul Walmsley
2012-04-11 22:23 ` Mark A. Greer
2012-04-11 22:23 ` Mark A. Greer
2012-04-11 22:47 ` Paul Walmsley
2012-04-11 22:47 ` Paul Walmsley
2012-04-11 23:08 ` Mark A. Greer
2012-04-11 23:08 ` Mark A. Greer
2012-04-24 20:51 ` Mark A. Greer
2012-04-24 20:51 ` Mark A. Greer
2012-04-24 23:25 ` Mark A. Greer
2012-04-24 23:25 ` Mark A. Greer
2012-04-27 21:12 ` Kevin Hilman
2012-04-27 21:12 ` Kevin Hilman
2012-04-27 21:55 ` Mark A. Greer
2012-04-27 21:55 ` Mark A. Greer
2012-04-30 21:34 ` Mark A. Greer
2012-04-30 21:34 ` Mark A. Greer
2012-04-30 22:00 ` Kevin Hilman
2012-04-30 22:00 ` Kevin Hilman
2012-04-30 22:18 ` Mark A. Greer
2012-04-30 22:18 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 04/12] arm: omap3: am35x: Don't mark missing features as present Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 05/12] arm: omap3: am35x: Add PWROFF feature Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 22:46 ` Kevin Hilman
2012-04-11 22:46 ` Kevin Hilman
2012-04-11 23:11 ` Mark A. Greer
2012-04-11 23:11 ` Mark A. Greer
2012-04-24 4:36 ` Mark A. Greer
2012-04-24 4:36 ` Mark A. Greer
2012-04-27 21:07 ` Kevin Hilman
2012-04-27 21:07 ` Kevin Hilman
2012-04-30 22:08 ` Mark A. Greer
2012-04-30 22:08 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 06/12] arm: omap3: am35x: Add full PWRDM_POWER_INACTIVE support Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 20:56 ` Jean Pihet
2012-04-11 20:56 ` Jean Pihet
2012-04-11 21:08 ` Paul Walmsley
2012-04-11 21:08 ` Paul Walmsley
2012-04-11 21:14 ` Mark A. Greer
2012-04-11 21:14 ` Mark A. Greer
2012-04-11 21:15 ` Jean Pihet
2012-04-11 21:15 ` Jean Pihet
2012-04-11 21:12 ` Mark A. Greer
2012-04-11 21:12 ` Mark A. Greer
2012-04-11 22:17 ` Paul Walmsley
2012-04-11 22:17 ` Paul Walmsley
2012-04-11 19:05 ` [PATCH 07/12] arm: omap3: am35x: Set proper powerdomain states Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 21:53 ` Paul Walmsley
2012-04-11 21:53 ` Paul Walmsley
2012-04-11 22:40 ` Mark A. Greer
2012-04-11 22:40 ` Mark A. Greer
2012-04-12 0:24 ` Jon Hunter
2012-04-12 0:24 ` Jon Hunter
2012-04-12 2:19 ` Mark A. Greer
2012-04-12 2:19 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 08/12] arm: omap3: am35x: Fix clockdomain dependencies Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 21:44 ` Paul Walmsley
2012-04-11 21:44 ` Paul Walmsley
2012-04-11 21:55 ` Mark A. Greer
2012-04-11 21:55 ` Mark A. Greer
2012-04-11 22:04 ` Paul Walmsley
2012-04-11 22:04 ` Paul Walmsley
2012-04-11 22:49 ` Mark A. Greer
2012-04-11 22:49 ` Mark A. Greer
2012-04-11 23:49 ` Paul Walmsley
2012-04-11 23:49 ` Paul Walmsley
2012-04-12 2:23 ` Mark A. Greer
2012-04-12 2:23 ` Mark A. Greer
2012-04-12 2:29 ` Paul Walmsley
2012-04-12 2:29 ` Paul Walmsley
2012-04-12 23:00 ` Mark A. Greer
2012-04-12 23:00 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 09/12] arm: omap3: am35x: Add SDRC EMIF4 feature Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 21:29 ` Paul Walmsley
2012-04-11 21:29 ` Paul Walmsley
2012-04-11 22:50 ` Mark A. Greer
2012-04-11 22:50 ` Mark A. Greer
2012-04-11 22:56 ` Paul Walmsley
2012-04-11 22:56 ` Paul Walmsley
2012-04-11 23:23 ` Mark A. Greer
2012-04-11 23:23 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 10/12] arm: omap3: am35x: Add minimal EMIF4 support Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 21:31 ` Paul Walmsley
2012-04-11 21:31 ` Paul Walmsley
2012-04-11 23:22 ` Mark A. Greer
2012-04-11 23:22 ` Mark A. Greer
2012-04-11 19:05 ` [PATCH 11/12] arm: omap3: am35x: Add do_wfi routine for EMIF4 submodules Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 22:35 ` Kevin Hilman
2012-04-11 22:35 ` Kevin Hilman
2012-04-11 23:26 ` Mark A. Greer
2012-04-11 23:26 ` Mark A. Greer
2012-04-11 22:36 ` Paul Walmsley
2012-04-11 22:36 ` Paul Walmsley
2012-04-13 0:12 ` Mark A. Greer
2012-04-13 0:12 ` Mark A. Greer
2012-04-11 22:54 ` Paul Walmsley
2012-04-11 22:54 ` Paul Walmsley
2012-04-11 19:05 ` [PATCH 12/12] arm: omap3: am35x: Register davinci_mdio before davinci_emac Mark A. Greer
2012-04-11 19:05 ` Mark A. Greer
2012-04-11 21:24 ` Paul Walmsley
2012-04-11 21:24 ` Paul Walmsley
2012-04-11 22:00 ` Mark A. Greer
2012-04-11 22:00 ` Mark A. Greer
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