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| author | Vladimir Murzin <vladimir.murzin@arm.com> | 2017-05-24 11:24:31 +0100 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2017-06-30 10:03:10 -0700 |
| commit | 1b11d39e6a6864a9dfb64e2c3ac03090e3b34399 (patch) | |
| tree | 0cc05ea30843b0a613eb1e1b2d7a6078c88e815c /arch/arm | |
| parent | 1c51c429f30ea10428337f3a33c12059ba59f668 (diff) | |
| download | linux-1b11d39e6a6864a9dfb64e2c3ac03090e3b34399.tar.gz | |
ARM: NOMMU: Set ARM_DMA_MEM_BUFFERABLE for M-class cpus
Now, we have dedicated non-cacheable region for consistent DMA operations. However, that region can still be marked as bufferable by MPU, so it'd be safer to have barriers by default. M-class machines that didn't need it until now also likely won't need it in the future, therefore, we offer this as an option. Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Andras Szemzo <sza@esh.hu> Tested-by: Alexandre TORGUE <alexandre.torgue@st.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com> Acked-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/mm/Kconfig | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index c6c4c9c8824b..877a0e3fd17d 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -1045,8 +1045,8 @@ config ARM_L1_CACHE_SHIFT default 5 config ARM_DMA_MEM_BUFFERABLE - bool "Use non-cacheable memory for DMA" if (CPU_V6 || CPU_V6K) && !CPU_V7 - default y if CPU_V6 || CPU_V6K || CPU_V7 + bool "Use non-cacheable memory for DMA" if (CPU_V6 || CPU_V6K || CPU_V7M) && !CPU_V7 + default y if CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M help Historically, the kernel has used strongly ordered mappings to provide DMA coherent memory. With the advent of ARMv7, mapping @@ -1061,6 +1061,10 @@ config ARM_DMA_MEM_BUFFERABLE and therefore turning this on may result in unpredictable driver behaviour. Therefore, we offer this as an option. + On some of the beefier ARMv7-M machines (with DMA and write + buffers) you likely want this enabled, while those that + didn't need it until now also won't need it in the future. + You are recommended say 'Y' here and debug any affected drivers. config ARM_HEAVY_MB |