From mboxrd@z Thu Jan  1 00:00:00 1970
From: James Bottomley <James.Bottomley@steeleye.com>
Subject: Re: Proposal for new generic device API: dma_get_required_mask()
Date: 17 Jun 2004 15:12:17 -0500
Sender: linux-scsi-owner@vger.kernel.org
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	<20040617152818.GZ20511@parcelfarce.linux.theplanet.co.uk>
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To: Matthew Wilcox <willy@debian.org>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>, SCSI Mailing List <linux-scsi@vger.kernel.org>

On Thu, 2004-06-17 at 10:28, Matthew Wilcox wrote:
> So let's look at the sym2 implementation to see how this would work.
> A straight diff -u is not terribly helpful, So let's try a more verbose
> context diff:

actually, no.  I'm proposing an additional API, not a modification to
dma_set_mask(), so the new code would read

       struct pci_dev *pdev = &np->s.device;
 
        if (np->features & FE_DAC) {
               if (dma_set_mask(&pdev->dev, 0xffffffffffULL))
	               if (dma_get_required_mask(&pdev->dev) > 0xffffffffUL)
        	               goto use_dac;
		
        }
 
       dma_set_mask(&pdev->dev, 0xffffffffUL);
        return 0;
  
  use_dac:
       np->use_dac = 1;
       printf_info("%s: using 64 bit DMA addressing\n", sym_name(np));
       return 0;

James