Subject: Re: [PATCH] libata-sff: Don't call bmdma_stop on non DMA capable
	controllers
From: David Woodhouse <dwmw2@infradead.org>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: Jeff Garzik <jgarzik@pobox.com>, Alan <alan@lxorguk.ukuu.org.uk>,
       torvalds@osdl.org, linux-kernel@vger.kernel.org
In-Reply-To: <20070125162255.GF31145@flint.arm.linux.org.uk>
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	 <45B8D810.3030501@pobox.com>
	 <20070125162255.GF31145@flint.arm.linux.org.uk>
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Date: Fri, 26 Jan 2007 00:26:15 +0800
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On Thu, 2007-01-25 at 16:22 +0000, Russell King wrote:
> The zero DMA address is absolutely and totally valid.  It might not
> correspond with physical address zero on platforms.
> 
> Also, DMA address zero is not the same as NULL. 

This isn't actually "DMA address" in that context -- it's the I/O port
number at which the controller's BM-DMA control registers reside. But
still it can be zero.

-- 
dwmw2

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