Messages in this thread Patch in this message | | | Date | Thu, 28 Apr 2022 12:12:39 +0100 | Subject | Re: [PATCH 5/5] iommu/sun50i: Ensure the IOMMU can be used for DMA | From | Robin Murphy <> |
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On 2022-04-28 02:04, Samuel Holland wrote: > So far, the driver has relied on arch/arm64/Kconfig to select IOMMU_DMA. > Unsurprisingly, this does not work on RISC-V, so the driver must select > IOMMU_DMA itself.
No, IOMMU_DMA should only be selected by the architecture code that's also responsible for calling iommu_setup_dma_ops(). Without that, this select will do nothing other than add some unused code to the kernel image.
I appreciate that the current state of the x86 IOMMU drivers being tightly-coupled to the x86 arch code might be confusing (which reminds me I'd totally forgotten about [1]). I'm about to start reworking the whole area anyway, but for now please just follow the existing intent.
Thanks, Robin.
[1] https://lore.kernel.org/linux-iommu/9ba6f2e8568a3ff6a94fade66668d99705433c44.1631536879.git.robin.murphy@arm.com/
> Signed-off-by: Samuel Holland <samuel@sholland.org> > --- > > drivers/iommu/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index c79a0df090c0..70a0bfa6d907 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -223,6 +223,7 @@ config SUN50I_IOMMU > depends on ARCH_SUNXI || COMPILE_TEST > select ARM_DMA_USE_IOMMU > select IOMMU_API > + select IOMMU_DMA > help > Support for the IOMMU introduced in the Allwinner H6 SoCs. >
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