[U-Boot] [PATCH v4 3/6] mcx: Disable DCACHE since USB EHCI is enabled

[Marek Vasut]

Dear Ilya Yanok,

> Dear Marek,
> 
> 28.06.2012 02:48, Marek Vasut wrote:
> >> Sorry for missing this discussion. I think compile-time disabling of the
> >> cache is too brutal.
> >> ehci-hcd cache handling is broken anyway: doing unaligned
> >> flushes/invalidates is a bug, and we know for sure that upper layers
> >> don't care about alignment (and I bet ehci-hcd does this even for its
> >> internal buffers). So what's the point in all this cache handling in
> >> ehci-hcd? It's not going to work anyway and just produces problems. So I
> >> suggest to just disable all this stuff until generic code will be fixed.
> >> Alternatively we can do bounce-buffering inside driver.
> > 
> > We should rather introduce generic bounce buffer. But the upper layers
> > are getting fixed recently so we should be getting there.
> 
> Really? Don't forget my old patch [1] then ;)
> Still I think we should rip off all the cache stuff from ehci-hcd until
> all patches for upper layers are included. Again, this stuff doesn't do
> proper things now anyway and USB won't work with dcache enabled.

Have you tested? I enabled dcache on m28 and tried asix ethernet (needed a 
patch) and loading from ext2 and vfat (worked).

> BTW, I think this was under #ifdef CONFIG_EHCI_DCACHE last time looked
> at it. Was this changed by your commit? I think that's the source of the
> problem this series tries to address: you've taken buggy code out of
> #ifdef ;) I think it's better to just put it back until upper layers
> won't be fixed.
> 
> Regards, Ilya.
> 
> [1] http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/114235

Best regards,
Marek Vasut