Re: [PATCH] net/macb: Use dmapool to align descriptors on 64bits

From: Nicolas Ferre
Date: Tue Dec 04 2012 - 12:18:44 EST


On 12/03/2012 03:01 PM, Ben Hutchings :
> On Mon, 2012-12-03 at 13:15 +0100, Nicolas Ferre wrote:
>> Depending on datapath, some revisions of GEM need
>> 64bits aligned descriptors. Use dmapool to allocate
>> these descriptors.
>> Note that different size between RX and TX rings
>> leads to the creation of two pools.
>>
>> Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
> [...]
>
> dma_alloc_coherent() allocates whole pages, which I think is quite
> enough alignment. You can't save memory by doing this, since each pool
> needs at least one page. So what is this change meant to achieve?

Well... I guess we can forget this patch then ;-)

Thanks, best regards,
--
Nicolas Ferre
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