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

Tom Rini
2012-06-28T22:34:54Z

On Fri, Jun 29, 2012 at 12:01:58AM +0200, Marek Vasut wrote:
> Dear Tom Rini,
>
> > On 06/28/2012 07:37 AM, Marek Vasut wrote:
> > > 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).
> >
> > So then we have more places that accidentially aligned to 32bytes since
> > this does not work on TI parts which require 64byte alignment.
>
> Oh, this is very good it's broken. People actually started whining. Now we have
> to wait until they start identifying the problematic places and fixing them.

Uh-hunh. So I guess for v2012.07 we'll build-time disable dcache for
beagle and omap3_evm and leave it on for mcx and see who has time and
hardware to fix things for v2012.10.

--
Tom
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