Re: [rtc-linux] Re: [RFC 09/15] media: platform: Add missing MFD_SYSCON dependency on HAS_IOMEM

Arnd Bergmann
2016-03-03T13:05:33Z

On Thursday 03 March 2016 21:40:23 Krzysztof Kozlowski wrote:
> >> select MFD_SYSCON
> >> diff --git a/drivers/media/platform/exynos4-is/Kconfig b/drivers/media/platform/exynos4-is/Kconfig
> >> index 57d42c6172c5..c4317b99d257 100644
> >> --- a/drivers/media/platform/exynos4-is/Kconfig
> >> +++ b/drivers/media/platform/exynos4-is/Kconfig
> >> @@ -17,6 +17,7 @@ config VIDEO_S5P_FIMC
> >> tristate "S5P/EXYNOS4 FIMC/CAMIF camera interface driver"
> >> depends on I2C
> >> depends on HAS_DMA
> >> + depends on HAS_IOMEM # For MFD_SYSCON
> >> select VIDEOBUF2_DMA_CONTIG
> >> select V4L2_MEM2MEM_DEV
> >
> > This is guarded by HAS_DMA, which implies HAS_IOMEM afaik.
>
> Looking at Kconfigs - no, it is not implied (or am I missing
> something)... and sometimes dependency on HAS_IOMEM is next to
> HAS_DMA.
>
>

Ah, you are right: UML has no DMA and no IOMEM, but s390 can
have IOMEM (if PCI is enabled) and always sets HAS_DMA.

In practice, I think the HAS_DMA symbol is not as well-defined
as it should be, it basically refers to the presence of the dma-mapping.h
API, and that only really makes sense when you also have IOMEM,
so there might be an implied dependency between the two, but it's
not enforced or actually true.

Arnd