On Thu, 2010-02-25 at 08:12 +1100, Benjamin Herrenschmidt wrote: > 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() ? :-) Actually, that can be wrong depending on the implementation. The problem is incoherency of the kernel page (dirty) with respect to user space aliases (clean). What has to happen on parisc is that the kernel alias needs flushing. We can guarantee the userspace aliases to be clean (and not moved in). We wouldn't want to incur the expense of flushing the user space pages as well. > 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. Right, so it's the responsibility of the API used by the subsystem. Thus Caitlin's pio_kmap seems the right one ... I don't understand what the additional problems are. James -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
