[U-Boot] [PATCH 1/3] ARM: implement some Cortex-A9 errata workarounds

[Tom Warren]

Albert,

> -----Original Message-----
> From: Albert ARIBAUD [mailto:albert.u.boot at aribaud.net]
> Sent: Monday, March 04, 2013 11:00 AM
> To: Tom Warren
> Cc: Stephen Warren; u-boot at lists.denx.de; Stephen Warren; Tom Warren
> Subject: Re: [U-Boot] [PATCH 1/3] ARM: implement some Cortex-A9 errata
> workarounds
> 
> Hi Tom,
> 
> On Mon, 4 Mar 2013 08:30:11 -0800, Tom Warren <TWarren at nvidia.com>
> wrote:
> 
> > Stephen & Albert,
> >
> > > -----Original Message-----
> > > From: Stephen Warren [mailto:swarren at wwwdotorg.org]
> > > Sent: Friday, March 01, 2013 2:54 PM
> > > To: Tom Warren
> > > Cc: u-boot at lists.denx.de; Stephen Warren
> > > Subject: Re: [U-Boot] [PATCH 1/3] ARM: implement some Cortex-A9
> > > errata workarounds
> > >
> > > On 02/28/2013 10:08 AM, Stephen Warren wrote:
> > > > On 02/26/2013 03:28 PM, Stephen Warren wrote:
> > > >> From: Stephen Warren <swarren at nvidia.com>
> > > >>
> > > >> Various errata exist in the Cortex-A9 CPU, and may be worked
> > > >> around by setting some bits in a CP15 diagnostic register. Add
> > > >> code to implement the workarounds, enabled by new CONFIG_ options.
> > > >>
> > > >> This code was taken from the Linux kernel, v3.8,
> > > >> arch/arm/mm/proc-v7.S, and modified to remove the logic to
> > > >> conditionally apply the WAR (since we know exactly which CPU
> > > >> we're running on given the U-Boot configuration), and use r0
> > > >> instead of r10 for consistency with the rest of U-Boot's
> cpu_init_cp15().
> > > >
> > > > Hmmm. Lets hold off on this series; there are some conditions
> > > > under which the kernel has to be able to apply these WARs anyway
> > > > (e.g. SMP CPU power saving), which may impact which of the WARs
> > > > the bootloader should apply even when booting the initial CPU 0.
> > > > I'll repost once that's been resolved.
> > >
> > > Tom,
> > >
> > > It looks like the bootloader should always apply these WARs for CPU 0.
> > > We just have to make sure that the kernel applies them for CPUs 1..n
> > > if/when running in secure mode.
> > >
> > > In other words, I think these patches are good to go in as-is. Since
> > > there are no changes to the patches, I won't repost them, unless you
> need me to.
> >
> > I can take these in via the Tegra tree, but the bulk of the changes are
> for ARM, not Tegra.
> > Albert - do you want to take this directly into the ARM repo, or would you
> prefer me to take it?
> 
> I will take them in tonight.
Thanks. I'll assign the Tegra patch to you in Patchwork & take 'em out of u-boot-tegra/next.

Tom
> 
> > Tom
> 
> Amicalement,
> --
> Albert.
--
nvpublic