From 38541bf48588d5350e45167510766f8bb6ba6582 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 25 Nov 2015 17:32:17 +0100 Subject: [PATCH] ARM: no longer force unbuffered DMA for realview Commit 42c4dafe803dca ("ARM: 6202/1: Do not ARM_DMA_MEM_BUFFERABLE on RealView boards with L210/L220") changed the generic setting for ARM_DMA_MEM_BUFFERABLE to be disabled on any Realview kernel that includes support for any of the ARM11 variations. Doing this was required to allow doing DMA without a lockup in the l2x0 cache controller on the Realview platform. Unfortunately, in a kernel that also contains support for any ARMv7 based machine, the same change makes it impossible to do DMA on ARMv7, which gets in the way of enabling multiplatform support on Realview. As confirmed by Catalin Marinas and Linus Walleij, the current code for Realview that we have in the kernel does not actually perform any DMA, and this is unlikely to change in the future. Therefore we can revert 42c4dafe803dca without introducing regressions, but we must never start using DMA on this platform in the future. Signed-off-by: Arnd Bergmann Cc: Russell King Signed-off-by: Linus Walleij --- arch/arm/mm/Kconfig | 2 -- 1 file changed, 2 deletions(-) diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 4121886..76f65f2 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -1005,8 +1005,6 @@ config ARM_L1_CACHE_SHIFT config ARM_DMA_MEM_BUFFERABLE bool "Use non-cacheable memory for DMA" if (CPU_V6 || CPU_V6K) && !CPU_V7 - depends on !(MACH_REALVIEW_PB1176 || REALVIEW_EB_ARM11MP || \ - MACH_REALVIEW_PB11MP) default y if CPU_V6 || CPU_V6K || CPU_V7 help Historically, the kernel has used strongly ordered mappings to -- 2.7.4