On Wed, 2010-02-24 at 08:16 +0100, Oliver Neukum wrote:

I don't know. The issue seems quite complex. It would seem better to
centralize it as far as practical. Do you have a wrapper drivers could
call?

flush_dcache_page() ? :-)

Now, the subsystem might be the one to know whether something is mapped
into userspace or not (v4l in our case) in which case a wrapper could be
created.

Cheers,
Ben.