From: "Mark A. Greer" <mgreer@animalcreek.com>
To: Paul Walmsley <paul@pwsan.com>
Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
khilman@ti.com
Subject: Re: [PATCH 03/12] arm: omap3: Only sleep in cpuidle driver if I/O wake-ups work
Date: Wed, 11 Apr 2012 15:23:13 -0700 [thread overview]
Message-ID: <20120411222313.GC31197@animalcreek.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1204111532280.29473@utopia.booyaka.com>
On Wed, Apr 11, 2012 at 03:37:47PM -0600, Paul Walmsley wrote:
>
> On Wed, 11 Apr 2012, Mark A. Greer wrote:
>
> > From: "Mark A. Greer" <mgreer@animalcreek.com>
> >
> > Currently, the OMAP3 cpuidle driver calls omap3_enter_idle()
> > which calls omap_sram_idle(). omap_sram_idle() 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).
> >
> > To handle this, follow the same path in omap3_enter_idle()
> > that would be followed if an interrupt were pending.
>
> I don't quite understand this patch. Are you saying that AM3517/3505
> can't wake from WFI? That would seem odd.
No, I'm saying that I/O doesn't seem to wake it up from the WFI.
I've learned to not trust the am35x TRM much so I'm pretty much
feeling my way along in the dark. I do know that without this
patch, the system is extremely slow which I believe is from it
only returning from the WFI because of a timer expiration or
something like that.
> There are other sources of wakeup on the system other than I/O wakeup.
> I/O wakeup only applies to wakeups from the I/O pads when the chip is in
> RETENTION or OFF. And as I understand it, neither of those apply to
> AM3517/3505?
Hmm, its true that RETENTION and OFF aren't supported. It does wake up
occasionally (as mentioned above) it just seems that I/O doesn't wake
it up. I may be mistaken. I'm only going from what I've seen since and
the TRM seems to have lots of errors so I'm not sure what to trust in it.
> Even if I/O wakeups aren't supported, many of the IP blocks on the system
> should be able to cause the ARM to exit WFI by asserting their
> SWAKEUP lines and raising their interrupt lines.
Okay, but that doesn't seem to be working. I'll look some more to see
why they aren't working.
> So this change doesn't seem quite right to me...
>
> More broadly, if AM3517/3505 only supports powerdomains ON, then you
> should probably use your own CPUIdle driver that doesn't touch the
> powerdomain states at all.
Okay, I can do that.
Mark
--
next prev parent reply other threads:[~2012-04-11 22:23 UTC|newest]
Thread overview: 63+ 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 ` [PATCH 01/12] arm: omap3: Only access IVA if one exists 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 21:38 ` Paul Walmsley
2012-04-11 23:42 ` Jon Hunter
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 21:37 ` Paul Walmsley
2012-04-11 22:23 ` Mark A. Greer [this message]
2012-04-11 22:47 ` Paul Walmsley
2012-04-11 23:08 ` Mark A. Greer
2012-04-24 20:51 ` Mark A. Greer
2012-04-24 23:25 ` Mark A. Greer
2012-04-27 21:12 ` Kevin Hilman
2012-04-27 21:55 ` Mark A. Greer
2012-04-30 21:34 ` Mark A. Greer
2012-04-30 22:00 ` Kevin Hilman
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 ` [PATCH 05/12] arm: omap3: am35x: Add PWROFF feature Mark A. Greer
2012-04-11 22:46 ` Kevin Hilman
2012-04-11 23:11 ` Mark A. Greer
2012-04-24 4:36 ` Mark A. Greer
2012-04-27 21:07 ` Kevin Hilman
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 20:56 ` Jean Pihet
2012-04-11 21:08 ` Paul Walmsley
2012-04-11 21:14 ` Mark A. Greer
2012-04-11 21:15 ` Jean Pihet
2012-04-11 21:12 ` Mark A. Greer
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 21:53 ` Paul Walmsley
2012-04-11 22:40 ` Mark A. Greer
2012-04-12 0:24 ` Jon Hunter
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 21:44 ` Paul Walmsley
2012-04-11 21:55 ` Mark A. Greer
2012-04-11 22:04 ` Paul Walmsley
2012-04-11 22:49 ` Mark A. Greer
2012-04-11 23:49 ` Paul Walmsley
2012-04-12 2:23 ` Mark A. Greer
2012-04-12 2:29 ` Paul Walmsley
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 21:29 ` Paul Walmsley
2012-04-11 22:50 ` Mark A. Greer
2012-04-11 22:56 ` Paul Walmsley
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 21:31 ` Paul Walmsley
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 22:35 ` Kevin Hilman
2012-04-11 23:26 ` Mark A. Greer
2012-04-11 22:36 ` Paul Walmsley
2012-04-13 0:12 ` Mark A. Greer
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 21:24 ` Paul Walmsley
2012-04-11 22:00 ` Mark A. Greer
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