From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Luis R. Rodriguez" <lrodriguez@atheros.com>
Cc: Jiri Slaby <jirislaby@gmail.com>,
Nick Kossifidis <mickflemm@gmail.com>,
devel@driverdev.osuosl.org, ath9k-devel@venema.h4ckr.net,
linux-wireless@vger.kernel.org,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Jeff Garzik <jeff@garzik.org>
Subject: Re: [PATCH 3/4] ath5k: define ath_common ops
Date: Fri, 11 Sep 2009 07:24:40 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.01.0909110720210.3654@localhost.localdomain> (raw)
In-Reply-To: <43e72e890909110023k62a512bejd712a3449cc8328d@mail.gmail.com>
On Fri, 11 Sep 2009, Luis R. Rodriguez wrote:
>
> That is the way I had it originally before submission, and I
> completely agree its reasonable to not incur additional cost at the
> expense of having two separate read/write paths, and perhaps we should
> only incur the extra cost on routines shared between
> ath9k/ath9k/ath9k_htc. But -- is there really is a measurable cost
> penalty?
There's a measurable size penalty, at least.
In fact, if you know what kind of IO op it is (ie "it's always MMIO"),
you'd be even better using "writel()" directly, in which case it turns
into just a single store on most architectures, and doesn't cause all the
register save/restore of a function call.
Linus
next prev parent reply other threads:[~2009-09-11 14:25 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-11 1:34 [PATCH 0/4] atheros: implement common read/write ops Luis R. Rodriguez
2009-09-11 1:34 ` [PATCH 1/4] atheros/ath9k: add common read/write ops and port ath9k to use it Luis R. Rodriguez
2009-09-11 1:34 ` [PATCH 2/4] ath5k: allocate ath5k_hw prior to initializing hw Luis R. Rodriguez
2009-09-11 1:34 ` [PATCH 3/4] ath5k: define ath_common ops Luis R. Rodriguez
2009-09-11 1:42 ` Bob Copeland
2009-09-11 1:46 ` Luis R. Rodriguez
2009-09-11 6:16 ` Nick Kossifidis
2009-09-11 6:46 ` Jiri Slaby
2009-09-11 7:23 ` Luis R. Rodriguez
2009-09-11 11:35 ` Bob Copeland
2009-09-11 17:53 ` Luis R. Rodriguez
2009-09-11 14:24 ` Linus Torvalds [this message]
2009-09-11 17:43 ` Luis R. Rodriguez
2009-09-11 20:11 ` Linus Torvalds
2009-09-12 11:53 ` Jiri Slaby
2009-09-13 0:56 ` Luis R. Rodriguez
2009-09-11 1:34 ` [PATCH 4/4] atheros: define shared bssidmask setting Luis R. Rodriguez
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