[PATCH 00/11] Add L2 cache cleaning to generic CPU suspend

[Shawn Guo]

On Thu, Sep 01, 2011 at 11:57:54PM +0800, Shawn Guo wrote:
> On Thu, Sep 01, 2011 at 04:34:51PM +0100, Russell King - ARM Linux wrote:
> > On Thu, Sep 01, 2011 at 11:33:43PM +0800, Shawn Guo wrote:
> > > This is also the case on i.MX6Q, which L2 cache is retained during a
> > > suspend/resume cycle.  Currently, I have to call into the following
> > > before calling generic cpu_suspend() to clean/invalidate the entire
> > > L2 cache.
> > > 
> > > 	outer_flush_all();
> > > 	outer_disable();
> > > 
> > > But there is a wired thing on using generic cpu_resume().  I have to
> > > invalidate L1 before calling into cpu_resume() like below.
> > > 
> > > ENTRY(imx6q_cpu_resume)
> > >         bl      v7_invalidate_l1
> > >         b       cpu_resume
> > > ENDPROC(imx6q_cpu_resume)
> > > 
> > > ENTRY(imx6q_secondary_startup)
> > >         bl      v7_invalidate_l1
> > >         b       secondary_startup
> > > ENDPROC(imx6q_secondary_startup)
> > > 
> > > The v7_invalidate_l1() is the function copied from mach-tegra/headsmp.S,
> > > which has to be called before calling secondary_startup to boot
> > > secondary cores (same situation between Tegra and i.MX6Q).
> > 
> > Presumably that's because your L1 cache contains randomized data with
> > random validity (and presumably random dirtyness) at boot time - something
> > which unfortunately the ARM ARM permits.  I don't think we can go to the
> > extent of dealing with this in the generic code as it would unnecessarily
> > perturb those implementations which either the boot loader has already
> > sorted out that issue, or which don't have the issue at all.
> > 
> Yes, agreed.  It seems that Tegra and i.MX6Q are the only two CA9MP
> cases here.  But is it possible to maintain this v7_invalidate_l1()
> function in cache-v7.S, so that we do not need to duplicate it in
> platform codes?
> 
> > > Before applying this patch series, I have something like below actually
> > > working.
> > > 
> > > 
> > > 	outer_flush_all();
> > > 	outer_disable();
> > > 	imx_set_cpu_jump(0, imx6q_cpu_resume);
> > > 	/* Zzz ... */
> > > 	cpu_suspend(0, imx6q_suspend_finish);
> > > 
> > > I expect with you patches applied, I can still have it work with simply
> > > removing those two lines outer cache codes.
> > 
> > That should be the case.
> > 
> > > But unfortunately, I'm
> > > running into Oops when resuming back.  And I also have Oops with
> > > imx_set_cpu_jump(0, cpu_resume) which means skipping the
> > > v7_invalidate_l1() and calling generic cpu_resume() only.
> > 
> > Do you have a copy of the oops?
> > 
> 
Hi Russell,

After following your great debugging clue that we need to enable L2
before calling into generic cpu_resume(), now this patch series works
great for imx6q.  Thanks a lot, and here is my tag.

Tested-by: Shawn Guo <shawn.guo at linaro.org>

-- 
Regards,
Shawn