Message-ID: <40D359BB.3090106@pacbell.net>
Date: Fri, 18 Jun 2004 14:08:11 -0700
From: David Brownell <david-b@pacbell.net>
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To: James Bottomley <James.Bottomley@steeleye.com>
CC: Ian Molton <spyro@f2s.com>, Linux Kernel <linux-kernel@vger.kernel.org>,
       greg@kroah.com, tony@atomide.com, jamey.hicks@hp.com,
       joshua@joshuawise.com
Subject: Re: DMA API issues
References: <1087582845.1752.107.camel@mulgrave>	<20040618193544.48b88771.spyro@f2s.com>	<1087584769.2134.119.camel@mulgrave>	<20040618195721.0cf43ec2.spyro@f2s.com> <40D34078.5060909@pacbell.net> 	<20040618204438.35278560.spyro@f2s.com> <1087588627.2134.155.camel@mulgrave>
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James Bottomley wrote:
> On Fri, 2004-06-18 at 14:44, Ian Molton wrote:
> 
>>>For example, if usbaudio uses usb_buffer_alloc to stream data,
>>>that eliminates dma bouncing.  That's dma_alloc_coherent at
>>>its core ... it should allocate from that 32K region.
>>
>>Agreed.
> 
> 
> There are complications to this: not all platforms can access PCI memory
> directly.  That's why ioremap and memcpy_toio and friends exist.  What
> should happen on these platforms?

I'm not following you.  This isn't using the PCI DMA calls.
These dots don't connect:  different hardware needs different
solutions.  How would those calls make dma_alloc_coherent work?

- Dave

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