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authorWill Deacon <will.deacon@arm.com>2011-11-14 17:24:58 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-11-21 13:12:18 +0000
commit11ed0ba1754841316d4095478944300acf19acc3 (patch)
tree2b7b1002398ca3bd035ec69fbec92ac6648fadf6 /arch/arm/kernel
parent6fe4c6d466e95d31164f14b1ac4aefb51f0f4f82 (diff)
ARM: 7161/1: errata: no automatic store buffer drain
This patch implements a workaround for PL310 erratum 769419. On revisions of the PL310 prior to r3p2, the Store Buffer does not automatically drain. This can cause normal, non-cacheable writes to be retained when the memory system is idle, leading to suboptimal I/O performance for drivers using coherent DMA. This patch adds an optional wmb() call to the cpu_idle loop. On systems with an outer cache, this causes an explicit flush of the store buffer. Cc: stable@vger.kernel.org Acked-by: Catalin Marinas <catalin.marinas@arm.com> Tested-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel')
-rw-r--r--arch/arm/kernel/process.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 75316f0dd02..3d0c6fb74ae 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -192,6 +192,9 @@ void cpu_idle(void)
#endif
local_irq_disable();
+#ifdef CONFIG_PL310_ERRATA_769419
+ wmb();
+#endif
if (hlt_counter) {
local_irq_enable();
cpu_relax();