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From: Benjamin Herrenschmidt <>
Cc: Greg Kroah-Hartman <>,
	Al Viro <>,, David Miller <>,
	David Howells <>,
Subject: Re: [RFC/PATCH] iomap: Add specific address space __iomap for iomap pointers
Date: Mon, 18 Feb 2008 15:28:24 +1100	[thread overview]
Message-ID: <1203308904.6740.19.camel@pasglop> (raw)
In-Reply-To: <>

On Mon, 2008-02-18 at 14:35 +1100, Benjamin Herrenschmidt wrote:
> The current iomap stuff (pci_iomap, ioport_map, pcim_iomap, ...) is
> confusing as it returns pointers in the _miomem address space.
> However, even if that would work on some architectures, the result
> of those functions is -not- to be used as an __iomem, with accessors
> such as readl/writel, but only with the new brand of specific accessors
> (ioread32/iowrite32/...).

Willy and Al raised a good point off-list, is that in all effective
implementations of this, the MMIO case -does- use compatible virtual
addresses with ioremap, in fact even powerpc does.

Thus if we consider iomap as a kind of superset of the ioremap space
with a "hole" in it for PIO, it's fine to use the same address space
marker and it's fine to interchange the accessors when one -knows-
for sure it's dealing with memory and not IO.

Thus drop my patch,


      reply	other threads:[~2008-02-18  4:30 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-18  3:35 Benjamin Herrenschmidt
2008-02-18  4:28 ` Benjamin Herrenschmidt [this message]

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