[U-Boot] i.MX51: FEC: Cache coherency problem?

[David Jander]

On Tue, 19 Jul 2011 13:07:52 +0200
Matthias Weißer <weisserm at arcor.de> wrote:

> Dear Aneesh
> 
> Am 18.07.2011 18:16, schrieb Aneesh V:
> > commit c2dd0d45540397704de9b13287417d21049d34c6
> > armv7: integrate cache maintenance support
> >
> > In this patch I added a call to dcache_enable() at the beginning of
> > board_init_r() for ARM(i.e. as soon as relocation is over). As a result
> > D-cache will be enabled for all ARM platforms now unless
> > CONFIG_SYS_DCACHE_OFF is set.
> 
> Is this really a good idea? This will break a couple of boards using 
> non-cache-aware drivers. And there are a couple of them in u-boot. I 
> think d-cache should be opt-in rather then opt-out as long as there are 
> any drivers which didn't handle cached memory regions correct. i-cache 
> is much less problematic and can be enabled by default.
> 
> If d-cache will be enabled by default on ARM I think I have to send a 
> patch for one of my boards :-)

Exactly the issue I am having now... the fact that I was unaware of this patch
and generally don't have much experience with solving cache-related issues
apparently, made me waste a lot of time debugging the fec_mxc.c driver while
the driver itself wasn't really broken (at least not more than before).
Now I finally know what's wrong and am working on a proposed fix to make this
one driver cache-aware.

Best regards,

-- 
David Jander
Protonic Holland.