Re: linux-next: build failure after merge of the drm tree

[Alexandre Courbot]

On Tue, Nov 10, 2015 at 1:45 AM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> On Wed, Nov 04, 2015 at 08:22:26PM +1100, Stephen Rothwell wrote:
>> Hi Dave,
>>
>> After merging the drm tree, today's linux-next build (s390 allmodconfig)
>> failed like this:
>>
>> drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c:143:2: error: implicit declaration of function 'dma_to_phys' [-Werror=implicit-function-declaration]
>>
>> Caused by commit
>>
>>   69c4938249fb ("drm/nouveau/instmem/gk20a: use direct CPU access")
>>
>> Discovered after the release.
>>
> Still seen in next-20151109, affecting at least alpha, i386, parisc, s390,
> and xtensa, but probably other architectures as well.
>
> dma_to_phys() was until now not used from driver code, and is only declared
> for an architecture if it is used/needed there.

Mmm there doesn't seem to be a portable way of getting a physical
address from a DMA handle, which is what we are trying to do in this
code.

In that particular case a cast is enough though, so we should probably
just do that. I will send a patch for Ben/David to include in order to
fix this issue at least.
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