summaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorWill Deacon <will.deacon@arm.com>2011-11-14 17:24:58 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2011-12-09 09:21:36 -0800
commitb94342e75946ed88a3048602390633b9f047d5f2 (patch)
tree9f0eb5ecdcf146fc4e336753464f0284c173354a /arch
parentf8b35bffd3cc4ffd14ab9c07909cdc45a9006776 (diff)
ARM: 7161/1: errata: no automatic store buffer drain
commit 11ed0ba1754841316d4095478944300acf19acc3 upstream. 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. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/Kconfig12
-rw-r--r--arch/arm/kernel/process.c3
2 files changed, 15 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e516aa23af0f..b68faef7ca0c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1332,6 +1332,18 @@ config ATAGS_PROC
Should the atags used to boot the kernel be exported in an "atags"
file in procfs. Useful with kexec.
+config PL310_ERRATA_769419
+ bool "PL310 errata: no automatic Store Buffer drain"
+ depends on CACHE_L2X0
+ help
+ 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 option adds a write barrier to the cpu_idle loop so that,
+ on systems with an outer cache, the store buffer is drained
+ explicitly.
+
endmenu
menu "CPU Power Management"
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 0d96d0171c05..61f90d390547 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -156,6 +156,9 @@ void cpu_idle(void)
#endif
local_irq_disable();
+#ifdef CONFIG_PL310_ERRATA_769419
+ wmb();
+#endif
if (hlt_counter) {
local_irq_enable();
cpu_relax();