linux-kernel - Re: [PATCH] Clarify pci_iomap() usage for MMIO-only devices

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Message-ID: <46F0332D.3050704@garzik.org>
Date:	Tue, 18 Sep 2007 16:21:01 -0400
From:	Jeff Garzik <jeff@...zik.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	"Luis R. Rodriguez" <mcgrof@...il.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"John W. Linville" <linville@...driver.com>,
	linux-wireless <linux-wireless@...r.kernel.org>
Subject: Re: [PATCH] Clarify pci_iomap() usage for MMIO-only devices

Linus Torvalds wrote:
> Why do people insist on 
> using the old interfaces (and matching them with the new setup)?

readl/writel is [slightly] faster, and possibility of using even-write 
__raw_writel() exists, in the old interface...

  ...but pci_iomap() is a bus-friendly wrapper that handles a few checks 
and function calls for you, even if you know your device is always MMIO.

A new pci_mmio_map() helper, to be used with 100% MMIO hardware, might 
help eliminate confusion.

	Jeff

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