From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Doug Anderson <dianders@chromium.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
Abhilash Kesavan <a.kesavan@samsung.com>,
Andrew Bresticker <abrestic@chromium.org>,
Inderpal Singh <inderpal.s@samsung.com>,
Thomas Abraham <thomas.ab@samsung.com>,
"olof@lixom.net" <olof@lixom.net>,
Tushar Behera <trblinux@gmail.com>,
Kevin Hilman <khilman@linaro.org>,
Javier Martinez Canillas <javier.martinez@collabora.co.uk>,
"linux-samsung-soc@vger.kernel.org"
<linux-samsung-soc@vger.kernel.org>,
"linux@arm.linux.org.uk" <linux@arm.linux.org.uk>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ARM: EXYNOS: mcpm: Don't rely on firmware's secondary_cpu_start
Date: Mon, 9 Jun 2014 23:38:31 +0100 [thread overview]
Message-ID: <20140609223831.GB16889@e102568-lin.cambridge.arm.com> (raw)
In-Reply-To: <CAD=FV=X17PeJ6JPE9Qyc1QT07AvA2PTE69Q87gz9a6MdUHgi4A@mail.gmail.com>
On Mon, Jun 09, 2014 at 06:03:31PM +0100, Doug Anderson wrote:
[...]
> Cold boot and resume from suspend are detected via various special
> flags in various special locations. Resume from suspend looks at
> INFORM1 (0x10048004) for flags. This register is 0 during a cold boot
> and has special values set by the kernel at resume time.
>
> It also looks as if some code looks at 0x10040900 (PMU_SPARE0) to help
> tell initial cold boot and secondary CPU bringup.
Ok, thanks a lot. It looks like firmware paths should be ready to
detect cold vs warm boot, and hopefully do not rely on a specific
MPIDR to come up first out of power states.
> > I am asking to check if on this platform CPUidle (where the notion of
> > primary CPU disappears) has a chance to run properly.
>
> I believe it should be possible, but we don't have CPUidle implemented
> in our current system. Abhilash may be able to comment more.
I am interested in more insights, that's very helpful thanks.
> > Probably CPUidle won't attain idle states where IRAM content is lost, but I
> > am still worried about the primary vs secondaries firmware boot behaviour.
>
> I don't think iRAM can be turned off for CPUidle.
It might be added a system state but I doubt that too and if you are
relying on registers for jump addresses that's not even a problem in
the first place.
> > What happens on reboot from suspend to RAM (or to put it differently,
> > what does secure firmware do on reboot from suspend to RAM - in
> > particular how is the "jump" address to bootloader/kernel set ?)
>
> Should be described above now.
Thank you very much.
Lorenzo
next prev parent reply other threads:[~2014-06-09 22:38 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-06 21:43 [PATCH] ARM: EXYNOS: mcpm: Don't rely on firmware's secondary_cpu_start Doug Anderson
2014-06-06 22:35 ` Nicolas Pitre
2014-06-06 22:43 ` Doug Anderson
2014-06-06 22:46 ` Andrew Bresticker
2014-06-06 23:14 ` [PATCH v2] " Doug Anderson
2014-06-07 1:34 ` Nicolas Pitre
2014-06-09 18:09 ` Kevin Hilman
2014-06-09 20:05 ` Andrew Bresticker
2014-06-09 20:22 ` Nicolas Pitre
2014-06-09 20:35 ` Kevin Hilman
2014-06-09 20:55 ` Nicolas Pitre
2014-06-16 18:37 ` Doug Anderson
2014-06-16 18:47 ` Nicolas Pitre
2014-06-07 18:12 ` [PATCH] " Lorenzo Pieralisi
2014-06-09 17:03 ` Doug Anderson
2014-06-09 22:38 ` Lorenzo Pieralisi [this message]
2014-06-10 8:12 ` Chander Kashyap
2014-06-10 15:21 ` Doug Anderson
2014-06-10 15:49 ` Nicolas Pitre
2014-06-11 4:52 ` Chander Kashyap
2014-06-11 10:13 ` Lorenzo Pieralisi
2014-06-11 12:14 ` Chander Kashyap
2014-06-11 13:15 ` Lorenzo Pieralisi
2014-06-11 13:29 ` Chander Kashyap
2014-06-11 13:34 ` Abhilash Kesavan
2014-06-11 15:19 ` Doug Anderson
2014-06-11 15:28 ` Kukjin Kim
2014-06-13 11:54 ` Chander Kashyap
2014-06-13 13:29 ` Nicolas Pitre
2014-06-13 15:10 ` Doug Anderson
2014-06-16 7:40 ` Chander Kashyap
2014-06-16 18:35 ` Doug Anderson
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