Re: [PATCH v2 RFC/RFT 1/5] ARM: dma-mapping: Add fallback normal page allocations

From: Nicolin Chen
Date: Wed Apr 24 2019 - 15:38:49 EST

On Wed, Apr 24, 2019 at 09:26:52PM +0200, Christoph Hellwig wrote:
> On Wed, Apr 24, 2019 at 11:33:11AM -0700, Nicolin Chen wrote:
> > I feel it's similar to my previous set, which did most of these
> > internally except the renaming part. But Catalin had a concern
> > that some platforms might have limits on CMA range [1]. Will it
> > be still okay to do the fallback internally?
> >
> > [1: ]
> Catalins statement is correct, but I don't see how it applies to
> your patch. Your patch just ensures that the fallback we have
> in most callers is uniformly applied everywhere. The non-iommu
> callers will still need to select a specific zone and/or retry
> just the page allocator with other flags if the CMA (or fallback)
> page doesn't match what they need. dma-direct does this correctly
> and I think the arm32 allocator does as well, although it is a bit
> hard to follow sometimes.

Okay. I will revise and submit the patches then. I think we
can still discuss on this topic once we have the changes.