[U-Boot] OMAP3 performance regression in 2011.12

Tom Rini tom.rini at gmail.com
Mon Jan 9 16:11:07 CET 2012


On Mon, Jan 9, 2012 at 3:27 AM, Joe Woodward <jw at terrafix.co.uk> wrote:
> Commit "armv7: disable L2 cache in cleanup_before_linux()" on 6th Dec 2011 by Aneesh V adds the following:
>
> arch/arm/cpu/armv7/cpu.c:cleanup_before_linux()
>
> ...
> v7_out_cache_disable();
> ...
>
> The commit message implies this change was to make booting reliable on OMAP4 by disabling L2 cache before jumping to Linux.
>
> However, when running with a stock 3.2 Linux kernel on an OMAP3 it has the effect of massively reducing system performance (when running using an OMAP3-
> only 3.2 Linux Kernel on a GUSMTIX Overo OMAP3530).
>
> Therefore, I assume this means that the kernel isn't turning the L2 cache back on for an OMAP3 (at least with my kernel build)!
>
> So, my question is...
>
> Are there any Kconfig options in Linux that will re-enable the L2 cache (something obvious that I've missed), or is this commit just bad-news for OMAP3?

Are you certain that this is the commit that's causing your problem?
The kernel is responsible for turning the cache back on and has for a
long time, iirc.

-- 
Tom


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