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

From: Marek Szyprowski
Date: Wed Jan 13 2016 - 09:36:49 EST


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:
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:
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

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