diff options
| author | Will Deacon <will.deacon@arm.com> | 2011-11-14 17:24:58 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-12-09 09:21:36 -0800 |
| commit | b94342e75946ed88a3048602390633b9f047d5f2 (patch) | |
| tree | 9f0eb5ecdcf146fc4e336753464f0284c173354a | |
| parent | f8b35bffd3cc4ffd14ab9c07909cdc45a9006776 (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>
| -rw-r--r-- | arch/arm/Kconfig | 12 | ||||
| -rw-r--r-- | arch/arm/kernel/process.c | 3 |
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(); |