Messages in this thread | | | Subject | Re: [PATCH 1/2] iommu/mediatek: select ARM_DMA_USE_IOMMU | From | Robin Murphy <> | Date | Mon, 29 Feb 2016 10:37:40 +0000 |
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Hi Arnd,
On 29/02/16 09:19, Arnd Bergmann wrote: > The newly added Mediatek IOMMU driver uses the IOMMU_DMA infrastructure, > but unlike other such drivers, it does not select 'ARM_DMA_USE_IOMMU', > which is a prerequisite, leading to a link error: > > warning: (MTK_IOMMU) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT && NEED_SG_DMA_LENGTH)
Going off on a tangent, is it actually right for that to depend on a NEED_* symbol, or should that really be a select instead?
> drivers/iommu/built-in.o: In function `iommu_put_dma_cookie': > mtk_iommu.c:(.text+0x11fe): undefined reference to `put_iova_domain' > drivers/iommu/built-in.o: In function `iommu_dma_init_domain': > mtk_iommu.c:(.text+0x1316): undefined reference to `init_iova_domain' > drivers/iommu/built-in.o: In function `__iommu_dma_unmap': > mtk_iommu.c:(.text+0x1380): undefined reference to `find_iova' > > This adds the same select that the other drivers have. On a related > note, I wonder if we should just always select ARM_DMA_USE_IOMMU > whenever any IOMMU driver is enabled. Are there any cases where > we would enable an IOMMU but not use it?
You could use one solely for VFIO without caring about DMA ops - I think that's mostly how ARM SMMUs are being used in practice at the moment - but DMA-focused 'media' IOMMUs vastly outnumber 'virtualisation' IOMMUs on ARM, so it would probably make sense. We already have the equivalent "select IOMMU_DMA if IOMMU_SUPPORT" on arm64.
> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: 0df4fabe208d ("iommu/mediatek: Add mt8173 IOMMU driver") > --- > drivers/iommu/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index b325954cf8f8..ea0998921702 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -341,6 +341,7 @@ config MTK_IOMMU > bool "MTK IOMMU Support" > depends on ARM || ARM64 > depends on ARCH_MEDIATEK || COMPILE_TEST > + select ARM_DMA_USE_IOMMU
If going down this route, I'd be inclined to add an "if ARM" there, just for clarity.
> select IOMMU_API > select IOMMU_DMA
As above, this is already selected on arm64, and isn't used on 32-bit*, so could probably just be removed, especially if it leads to build issues.
Robin.
*yet, of course. I need to have a proper look over Marek's RFC ;)
> select IOMMU_IO_PGTABLE_ARMV7S >
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