linux-kernel - dma_alloc_coherent() on PPC32: physical addresses above 2G possible?

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Message-ID: <488385A7.4010509@s5r6.in-berlin.de>
Date:	Sun, 20 Jul 2008 20:36:23 +0200
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	linuxppc-dev@...abs.org
CC:	linux-kernel@...r.kernel.org
Subject: dma_alloc_coherent() on PPC32: physical addresses above 2G possible?

Hi all,

I have to implement a workaround for a PCI device which gets into 
trouble if descriptors are located at 32bit addresses, while 31bit 
addresses are fine.  I would like to avoid this workaround on machines 
on which dma_alloc_coherent() won't ever go at memory above 2 GB.

Is defined(CONFIG_PPC32) a safe test for this?  I'm under the impression 
that defined(CONFIG_X86_32) is safe.

Are there any other means to detect when the workaround can be omitted, 
at compile time or at runtime?

PS:  I don't want to set the DMA mask of this device to DMA_31BIT_MASK 
because that would be detrimental to other functions of the device. It's 
a TI TSB43AB22A FireWire controller.
-- 
Stefan Richter
-=====-==--- -=== =-=--
http://arcgraph.de/sr/
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