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

From: Thomas Petazzoni

Sent: 07 March 2017 18:12
Hello,

On Tue, 7 Mar 2017 17:24:21 +0000, David Laight wrote:

quoted

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.

	David