From mboxrd@z Thu Jan 1 00:00:00 1970 From: robin.murphy@arm.com (Robin Murphy) Date: Tue, 03 Mar 2015 13:10:34 +0000 Subject: [RFC PATCH v2 3/3] arm64: hook up IOMMU dma_ops In-Reply-To: <54F59565.7000807@huawei.com> References: <482b3b109a3d4818b1b1e693f488a919cf1bb707.1423226542.git.robin.murphy@arm.com> <54F59565.7000807@huawei.com> Message-ID: <54F5B2CA.9050907@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 03/03/15 11:05, leizhen wrote: > On 2015/2/6 22:55, Robin Murphy wrote: >> With iommu_dma_ops in place, hook them up to the configuration code, so >> IOMMU-fronted devices will get them automatically. >> >> Signed-off-by: Robin Murphy >> --- >> arch/arm64/Kconfig | 1 + >> arch/arm64/include/asm/dma-mapping.h | 11 ++++++----- >> arch/arm64/mm/dma-mapping.c | 15 +++++++++++++++ >> 3 files changed, 22 insertions(+), 5 deletions(-) >> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index b1f9a20..e2abcdc 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -66,6 +66,7 @@ config ARM64 >> select HAVE_PERF_USER_STACK_DUMP >> select HAVE_RCU_TABLE_FREE >> select HAVE_SYSCALL_TRACEPOINTS >> + select IOMMU_DMA if IOMMU_SUPPORT > > IOMMU_SUPPORT is selected above, so "if IOMMU_SUPPORT" can be omitted. > And I suggest putting "select IOMMU_DMA" next to "select IOMMU_SUPPORT". Not in this patch set it isn't ;) Omitting the "if IOMMU_SUPPORT" at this point results in this for me: *** Default configuration is based on 'defconfig' warning: (ARM64) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT && NEED_SG_DMA_LENGTH) Furthermore, if IOMMU_SUPPORT is selected anywhere I think it should be in defconfig, rather than here - if the user wants to leave out all the IOMMU drivers, then they should be able to turn off IOMMU_SUPPORT as well (since it makes no sense on its own), at which point the architecture then needs to make sure that IOMMU_DMA is deselected. Unless there's a more elegant way to enforce that, I think this "select...if..." needs to stay as it is. Robin.