linux-kernel - RE: [PATCH v2 04/28] ARM: mm: cache-l2x0: Add support for re-enabling l2x0

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Message-ID: <2f97ec8a084e590220e1548fc927b60e@mail.gmail.com>
Date:	Wed, 26 Jan 2011 00:02:15 +0530
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	Catalin Marinas <catalin.marinas@....com>,
	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Colin Cross <ccross@...roid.com>, linux-tegra@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, olof@...om.net,
	konkers@...roid.com, Linus Walleij <linus.walleij@...ricsson.com>,
	Tony Lindgren <tony@...mide.com>, linux-kernel@...r.kernel.org
Subject: RE: [PATCH v2 04/28] ARM: mm: cache-l2x0: Add support for re-enabling l2x0

> -----Original Message-----
> From: Catalin Marinas [mailto:catalin.marinas@....com]
> Sent: Tuesday, January 25, 2011 11:44 PM
> To: Russell King - ARM Linux
> Cc: Colin Cross; linux-tegra@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; olof@...om.net; konkers@...roid.com;
> Santosh Shilimkar; Linus Walleij; Tony Lindgren; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH v2 04/28] ARM: mm: cache-l2x0: Add support for
> re-enabling l2x0
>
> On Tue, 2011-01-25 at 15:41 +0000, Russell King - ARM Linux wrote:
> > I think we need to come up with some proper way to deal with
> cpuidle
> > which doesn't involve adding lots of globally visible functions to
> all
> > sorts of bits of code and having platforms call them individually,
> > otherwise this is going to get _really_ messy in the future.
> >
> > Maybe we need a notifier list which can be told when cpuidle
> events
> > happen, so that parts of the system such as VFP and L2 cache
> support
> > can do the right thing without having platforms add lots of stuff
> like
> >
> >         gic_secondary_init();
> >         gic_restore_interrupt_types();
> >         vfp_enable();
> >         l2x0_enable();
> >         twd_enable();
> >         ... etc ...
> >
> > in their SoC specific code.
>
> But do we need a strict order between such operations? The notifier
> call
> chain isn't too flexible.
>
I guess it does depends on how the archs have integrated a9. Example
on OMAP there are different power modes possible.
	1. CPU context ,TWD lost
	2. CPU context ,TWD + L1 is lost
	3. CPU context + L1 is lost + GIC lost
	4. CPU context + L1 is lost + GIC lost + L2 lost
So there is need to have flexibility of calling these function
based on power modes. I don't know how notifiers can give
this flexibility

Regards,
Santosh
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