Re: [PATCH] [media] media: Kconfig: add dependency of HAS_DMA

[Marek Szyprowski]

Hello,

On 2016-01-12 15:10, Sakari Ailus wrote:
> On Mon, Jan 11, 2016 at 06:23:11PM +0530, Sudip Mukherjee wrote:
> > On Wed, Dec 30, 2015 at 06:56:03PM +0530, Sudip Mukherjee wrote:
> > > The build of m32r allmodconfig fails with the error:
> > > drivers/media/v4l2-core/videobuf2-dma-contig.c:484:2:
> > > 	error: implicit declaration of function 'dma_get_cache_alignment'
> > >
> > > The build of videobuf2-dma-contig.c depends on HAS_DMA and it is
> > > correctly mentioned in the Kconfig but the symbol VIDEO_STI_BDISP also
> > > selects VIDEOBUF2_DMA_CONTIG, so it is trying to compile
> > > videobuf2-dma-contig.c even though HAS_DMA is not defined.
> > >
> > > Signed-off-by: Sudip Mukherjee <sudip@xxxxxxxxxxxxxxx>
> > > ---
> > A gentle ping. m32r allmodconfig still fails with next-20160111. Build
> > log is at:
> > https://travis-ci.org/sudipm-mukherjee/parport/jobs/101536379
> Hi Sudip,
>
> Even though the issue now manifests itself on m32r, the problem is wider
> than that: dma_get_cache_alignment() is only defined if CONFIG_HAS_DMA is
> set.
>
> I wonder if using videobuf2-dma-contig makes any sense if HAS_DMA is
> disabled, so perhaps it'd be possible to make it depend on HAS_DMA.

VIDEOBUF2_DMA_CONTIG already depends on HAS_DMA, but when driver use select
directive for enabling support for VIDEOBUF2_DMA_CONTIG, the dependencies
are not checked further. This is known limitation/feature of kconfig system.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland