From 11ed0ba1754841316d4095478944300acf19acc3 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 14 Nov 2011 17:24:58 +0100 Subject: 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 Tested-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 75316f0..3d0c6fb 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(); -- cgit v1.1