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Date: Mon, 23 Jul 2012 18:15:39 -0500
From: Timur Tabi <timur@freescale.com>
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To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH] powerpc/mm: add ZONE_NORMAL zone for 64 bit kernel
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Cc: Wood Scott-B07421 <B07421@freescale.com>,
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Benjamin Herrenschmidt wrote:
> Sure, that's the right way to go, I meant bits of pieces of the
> infrastructure in between. Why diverge from other archs gratuituously
> here ?

Ok, I'm confused.  Are you suggesting that drivers do this:

u64 fsl_dma_dmamask = DMA_BIT_MASK(36);
dev->dma_mask = &fsl_dma_dmamask;
v = dma_alloc_coherent(dev, ..., GFP_DMA32);

That is, set the DMA mask *and* set GFP_DMA32?  That seems redundant.

I don't understand why a driver would set GFP_DMA32 if it has already set
the mask.

-- 
Timur Tabi
Linux kernel developer at Freescale