USB mass storage and ARM cache coherency

[Russell King - ARM Linux]

On Fri, Feb 26, 2010 at 04:25:21PM +0000, Catalin Marinas wrote:
> For mmap'ed pages (and present in the page cache), is it guaranteed that
> the HCD driver won't write to it once it has been mapped into user
> space? If that's the case, it may solve the problem by just reversing
> the meaning of PG_arch_1 on ARM and assume that a newly allocated page
> has dirty D-cache by default.

I guess we could also set PG_arch_1 in the DMA API as well, to avoid the
unnecessary D cache flushing when clean pages get mapped into userspace.