[PATCHv3 net-next 21/22] net: mvpp2: set dma mask and coherent dma mask on PPv2.2

David Laight David.Laight at ACULAB.COM
Wed Mar 8 03:00:10 PST 2017

From: Thomas Petazzoni
> Sent: 07 March 2017 18:12
> Hello,
> On Tue, 7 Mar 2017 17:24:21 +0000, David Laight wrote:
> > Are the coherent mappings just used for ring structures?
> > If it might be reasonable to allocate them as a single entity,
> > thus guaranteeing they all reside in a single 4G region.
> Do we have the guarantee that a DMA coherent allocation will not span a
> 4G boundary?

I'm pretty sure they are guaranteed not to cross any boundary they don't have to.
So a 16k buffer won't cross a 16k boundary.


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