diff options
Diffstat (limited to 'arch/arm/mm')
| -rw-r--r-- | arch/arm/mm/Kconfig | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index c4ed9f93f646..573528d9c6d8 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -781,3 +781,22 @@ config ARM_L1_CACHE_SHIFT int default 6 if ARM_L1_CACHE_SHIFT_6 default 5 + +config ARM_DMA_MEM_BUFFERABLE + bool "Use non-cacheable memory for DMA" if CPU_V6 && !CPU_V7 + default y if CPU_V6 || CPU_V7 + help + Historically, the kernel has used strongly ordered mappings to + provide DMA coherent memory. With the advent of ARMv7, mapping + memory with differing types results in unpredictable behaviour, + so on these CPUs, this option is forced on. + + Multiple mappings with differing attributes is also unpredictable + on ARMv6 CPUs, but since they do not have aggressive speculative + prefetch, no harm appears to occur. + + However, drivers may be missing the necessary barriers for ARMv6, + and therefore turning this on may result in unpredictable driver + behaviour. Therefore, we offer this as an option. + + You are recommended say 'Y' here and debug any affected drivers. |