[U-Boot] [RFC] command/cache: Add flush_cache command

[Scott Wood <scottwood@freescale.com>]

On 03/20/2013 09:58:36 AM, Wolfgang Denk wrote:
> Dear Albert,
> 
> In message <20130320145927.2031b913@lilith> you wrote:
> >
> > I do understand what it does, but I still don't get why it should be
> > done, since precisely payload control transfer happens through  
> bootm and
> > the like which already properly flush cache.

It doesn't always happen through bootm.  Standalone apps use the "go"  
command.

> Full agrement.
> 
> > Is there an ARM multi-core target in U-Boot where U-Boot runs on
> > one core but its payload shall be started on another, "un-booted",
> > core, and which experiences issues due to the first core not  
> flushing
> > cache? If no existing target needs this, then this patch is  
> useless. If
> > there exists such a target and issue, then the right fix is not a  
> shell
> > command, it is a programmatic flush before the other core is  
> enabled,
> > so that it always sees correct RAM.
> 
> Agreed again.  As is, the patch was only adding dead code, as there
> are no users of the feature.

It's a user command!  How can it be dead code?  I don't know of a way  
to include a human user in a patchset...

> <nitpick>
> Also, it was added unconditionally which is a strict no-no as it just
> adds code-bloat to everyone, without benefit.
> </nitpick>

Only for boards which select CONFIG_CMD_CACHE... not sure how  
fine-grained it makes sense to make it.

-Scott