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

[Wolfgang Denk]

Dear Scott,

In message <1363890157.31522.14 at snotra> you wrote:
>
> As above it's from flash (I assume NOR) to RAM.  The "why" is to be =20
> able to run the code from RAM. :-P

* Why don't you run it form flash?

* Why do you insist on using the "go" command (instead of "bootm" with
  a IH_TYPE_STANDALONE image?

> > - eventually we should discourage the use of "go"; it may be
> >   conveniend when you know what you are doing, but if it's casuing
> >   such problems we might be better off recommending to use
> >   proper IH_TYPE_STANDALONE legacy images in combination with the
> >   bootm command instead.
>
> That or bootelf, sure.  I think there still should be some way to do it  
> manually, though.  bootm/bootelf probably wouldn't work for this use  
> case because it involves releasing other cores after the image is  
> copied/flushed, but before u-boot gives up control on the boot core.

The "releasing other cores" would then be a sub-command in the bootm
sequence?

> > - Also, instead of adding a new command, this could probably be
> >   scripted; I guess this should be roughly equivalent?
> > 
> >   	setenv flush_cache 'dc off;ic off;dc on;ic on'
>
> This assumes that we support those cache operations, that they affect  
> all relevant caches (on 85xx it only flushes L1, but at least on newer  
> chips L2 is relevant as well), and that there are no errata or  
> architectural limitations to running with caches off.

Indeed.

Best regards,

Wolfgang Denk

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