[U-Boot] [PATCH 2/4] cache_v7: Check for dcache enablement in dcache flush functions

[Marek Vasut]

Dear Tom Rini,

> On 06/14/2012 10:48 PM, R, Sricharan wrote:
> > Hi Tom,
> > 
> > On Fri, Jun 15, 2012 at 12:31 AM, Tom Rini <trini at ti.com> wrote:
> >> If we are built with D-CACHE enabled but have run 'dcache off' and then
> >> attempt to flush unaligned regions we spam the console with problems
> >> that aren't true (as the cache was off).
> >> 
> >   Today we do cache maintenance operations after the dcache is turned
> >   off. One example is before jumping to kernel, we try to invalidate the
> >   caches, in cache turned off state. So with this patch those
> >   maintenance calls will do nothing, which is not correct.
> 
> Ah yes,  But, shouldn't we be doing these same operations as part of
> turning the cache off?
> 
> >    If it is a problem with unaligned regions, then that is the only
> > 
> > thing to be fixed
> > 
> >   right ?. Just trying to understand why this change is required ?
> 
> The problem is that within the USB/network/filesystem stacks we have a
> lot of not cache safe alignments apparently.  Without this every '#' of
> a tftp gives a screen full of error printfs.  So tftp'ing a kernel takes
> minutes, not seconds, to complete.

I think we should augment uboot to disallow tftp, fatload etc. to cache-
unaligned address when caches are on ... this'd squash away the need for any 
shitty bounce buffers right away. Tom, will you be able to implement it, pretty 
please?

Of course, this doesn't squash the need for fixing FS code etc.

Best regards,
Marek Vasut