On 14/01/2019 09:41, Christoph Hellwig wrote:
Add a Kconfig symbol that indicates an architecture provides a
arch_dma_prep_coherent implementation, and provide a stub otherwise.
This will allow the generic dma-iommu code to it while still allowing
to be built for cache coherent architectures.
I've been pondering this for a while now, and I still can't really come
up with a case where arch_dma_prep_coherent() would need to behave
differently from arch_sync_dma_for_device(..., DMA_BIDIRECTIONAL). I
wonder if we could just save ourselves this little bit of complexity by
using that instead...
Robin.
Signed-off-by: Christoph Hellwig <h...@lst.de>
---
arch/arm64/Kconfig | 1 +
arch/csky/Kconfig | 1 +
include/linux/dma-noncoherent.h | 6 ++++++
kernel/dma/Kconfig | 3 +++
4 files changed, 11 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a4168d366127..ae3f581a9bcc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -13,6 +13,7 @@ config ARM64
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_DMA_COHERENT_TO_PFN
select ARCH_HAS_DMA_MMAP_PGPROT
+ select ARCH_HAS_DMA_PREP_COHERENT
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_FAST_MULTIPLIER
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 398113c845f5..8b84d4362ff6 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -1,5 +1,6 @@
config CSKY
def_bool y
+ select ARCH_HAS_DMA_PREP_COHERENT
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_USE_BUILTIN_BSWAP
diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h
index 69b36ed31a99..9741767e400f 100644
--- a/include/linux/dma-noncoherent.h
+++ b/include/linux/dma-noncoherent.h
@@ -72,6 +72,12 @@ static inline void arch_sync_dma_for_cpu_all(struct device
*dev)
}
#endif /* CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL */
+#ifdef CONFIG_ARCH_HAS_DMA_PREP_COHERENT
void arch_dma_prep_coherent(struct page *page, size_t size);
+#else
+static inline void arch_dma_prep_coherent(struct page *page, size_t size)
+{
+}
+#endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */
#endif /* _LINUX_DMA_NONCOHERENT_H */
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index ca88b867e7fe..541128a32c5d 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -29,6 +29,9 @@ config ARCH_HAS_SYNC_DMA_FOR_CPU
config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
bool
+config ARCH_HAS_DMA_PREP_COHERENT
+ bool
+
config ARCH_HAS_DMA_COHERENT_TO_PFN
bool
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