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

Arnd Bergmann arnd at arndb.de
Thu Mar 3 13:05:33 UTC 2016


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


More information about the devel mailing list