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Re: [PATCH] [RFC] gpu: host1x: shut up warning about DMA API misuse




On Thu, Apr 20, 2017 at 10:25:01AM +0200, Arnd Bergmann wrote:
> On Thu, Apr 20, 2017 at 9:02 AM, Mikko Perttunen <cyndis@xxxxxxxx> wrote:
> > I think we have a "policy" on Tegra that the DMA API will never allocate
> > using the IOMMU (Thierry can elaborate on this), which is why I wrote the
> > code with that assumption. Essentially, we have made the DMA API into the
> > API that allocates CPU-visible memory.
> 
> I don't think this can be a per-platform policy.
> 
> > Considering that, I'm wondering if we can just have a temporary local
> > dma_addr_t and then cast that to phys_addr_t, combined with a good comment?
> 
> That was my first approach, and it does address the warning, but
> I did not send it because it still felt too wrong.

Sounds to me like the warning is justified - it's saying that there's
something not right here which could be a problem.  So I'd say, don't
fix the warning, it's doing its job, highlighting a potential problem
with the code.

(Consider hiding the warning and then running on a platform where the
assumptions are broken.)

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