[PATCH 3/4] ath5k: define ath_common ops

Linus Torvalds torvalds at linux-foundation.org
Fri Sep 11 14:24:40 UTC 2009



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



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