Cc: Kumar Gala <galak@...>, David Brownell <dbrownell@...>, Pierre Ossman <drzeus-mmc@...>, Jochen Friedrich <jochen@...>, Timur Tabi <timur@...>, <linuxppc-dev@...>, <linux-kernel@...>, <spi-devel-general@...>
On Tue, Jun 03, 2008 at 12:07:49PM +0200, Marc Pignat wrote:
This isn't always practical. For example, host is using u8 register for
the status, so it might safely return u8 & mask, that will always fit
into int. Or very smart/adventurous authors might be aware that, for the
particular host, mask's bit isn't last, and safely do uXX & mask. :-)
The above is weak argument of course, since it is about optimization.
As an counter-evidence, the strict scheme that you described probably
less error prone. But is it? To implement it we'll need something like
WARN_ON(ret > 0 && ret != 1) to catch erroneous users. Take a closer
look though, will it catch uXX & lastbit case? Nope. :-)
We can catch bogus users though... via hack (_assuming_ that there
are no errno values of 1 << (sizeof(int) * 8 - 1)), i.e.
WARN_ON(ret == (1 << (sizeof(int) * 8 - 1)). Though, to do so, we don't
need the strict scheme, this debugging hack will work in the current
scheme too.
--
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2
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