Re: AW: PowerPC PCI DMA issues (prefetch/coherency?)

From: Josh Boyer <jwboyer@linux.vnet.ibm.com>
To: Adam Zilkie <azilkie@datacast.com>
Cc: Chris Pringle <chris.pringle@oxtel.com>,
	Andrea Zypchen <azypchen@intldata.ca>,
	linuxppc-dev@lists.ozlabs.org, Tom Burns <tburns@datacast.com>
Subject: Re: AW: PowerPC PCI DMA issues (prefetch/coherency?)
Date: Thu, 3 Sep 2009 12:21:15 -0400	[thread overview]
Message-ID: <20090903162115.GB22047@zod.rchland.ibm.com> (raw)
In-Reply-To: <1251993890.2548.14.camel@Adam>

On Thu, Sep 03, 2009 at 12:04:50PM -0400, Adam Zilkie wrote:
>Ben,
>
>Thanks for your info.
>
>Are you sure there is L2 cache on the 440?

It depends on which 440 SoC you have.  It also depends on that being 
configured in the kernel even if it does exist.

>I am seeing this problem with our custom IDE driver which is based on
>pretty old code. Our driver uses pci_alloc_consistent() to allocate the
>physical DMA memory and alloc_pages() to allocate a virtual page. It
>then uses pci_map_sg() to map to a scatter/gather buffer. Perhaps I
>should convert these to the DMA API calls as you suggest.

I would suggest updating the code.  I have no idea if that is the problem,
but it should probably be done anyway.

josh