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

[York Sun <yorksun@freescale.com>]

On 03/20/2013 12:15 PM, Tom Rini wrote:
> On Wed, Mar 20, 2013 at 11:43:15AM -0500, Scott Wood wrote:
>> 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.
> 
> So, to try and be a bit more verbose about this, for U-Boot applications
> which use 'go', we still need to ensure cache coherence, which is why
> bootm does a cache flush, we need some way to flush in this case.
> 
> And in this case you aren't better served by say bootelf ?

We have a user's case to release secondary cores to run user's
application which is in main memory. The secondary cores don't
necessarily share the cache with the core u-boot is running, depends on
hardware implementation. Without flushing the cache, those cores don't
have the correct code to fetch.

York