[U-Boot] [PATCH] ppc: Unlock cache-as-ram in a consistent manner

[Peter Tyser]

On Sat, 2009-07-11 at 07:52 +0800, Liu Dave-R63238 wrote:
> > Previously, non-e500 architectures only unlocked their data 
> > cache which
> > was used as early RAM when booting to Linux using the "bootm" command.
> > This change causes all PPC boards with 
> > CONFIG_SYS_INIT_RAM_LOCK defined
> > to unlock their data cache during U-Boot's initialization.  This
> > improves U-Boot performance and provides a common cache state when
> > booting to different OSes.
> > 
> > Signed-off-by: Peter Tyser <ptyser at xes-inc.com>
> > ---
> > I've tested this on 86xx boards, it'd be great if someone 
> > could test on
> > 83xx and 74xx/7xx.  85xx boards should not be affected by this change.
> > 
> > This change assumes 
> > http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/63423
> > has already been applied, or the lib/ppc patches in the diffs 
> > below can
> > be changed to lib_ppc.
> 
> I'm afraid some 83xx boards will not work after the patch is applied.
> It is some was assuming the data cache locked. (that is cache-inhibited)

Do those boards have CONFIG_SYS_INIT_RAM_LOCK defined?  I'm not familiar
with the 83xx arch, but would a board that required the data cache to be
disabled be considered broken?  ie shouldn't its MMU be setup up
correctly so that the cache could be enabled?

In any case, if this patch breaks the 83xx or 74xx/7xx architectures, I
hope the "86xx: Unlock l1 cache unconditionally" still makes it in.

Best,
Peter