summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--arch/arm/Kconfig15
-rw-r--r--arch/arm/include/asm/hardware/cache-l2x0.h1
-rw-r--r--arch/arm/mm/cache-l2x0.c6
3 files changed, 22 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 26d45e5b636..ba9fc213f34 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1177,6 +1177,21 @@ config ARM_ERRATA_743622
visible impact on the overall performance or power consumption of the
processor.
+config ARM_ERRATA_753970
+ bool "ARM errata: cache sync operation may be faulty"
+ depends on CACHE_PL310
+ help
+ This option enables the workaround for the 753970 PL310 (r3p0) erratum.
+
+ Under some condition the effect of cache sync operation on
+ the store buffer still remains when the operation completes.
+ This means that the store buffer is always asked to drain and
+ this prevents it from merging any further writes. The workaround
+ is to replace the normal offset of cache sync operation (0x730)
+ by another offset targeting an unmapped PL310 register 0x740.
+ This has the same effect as the cache sync operation: store buffer
+ drain and waiting for all buffers empty.
+
endmenu
source "arch/arm/common/Kconfig"
diff --git a/arch/arm/include/asm/hardware/cache-l2x0.h b/arch/arm/include/asm/hardware/cache-l2x0.h
index 5aeec1e1735..16bd4803158 100644
--- a/arch/arm/include/asm/hardware/cache-l2x0.h
+++ b/arch/arm/include/asm/hardware/cache-l2x0.h
@@ -36,6 +36,7 @@
#define L2X0_RAW_INTR_STAT 0x21C
#define L2X0_INTR_CLEAR 0x220
#define L2X0_CACHE_SYNC 0x730
+#define L2X0_DUMMY_REG 0x740
#define L2X0_INV_LINE_PA 0x770
#define L2X0_INV_WAY 0x77C
#define L2X0_CLEAN_LINE_PA 0x7B0
diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index 170c9bb9586..f2ce38e085d 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -49,7 +49,13 @@ static inline void cache_wait(void __iomem *reg, unsigned long mask)
static inline void cache_sync(void)
{
void __iomem *base = l2x0_base;
+
+#ifdef CONFIG_ARM_ERRATA_753970
+ /* write to an unmmapped register */
+ writel_relaxed(0, base + L2X0_DUMMY_REG);
+#else
writel_relaxed(0, base + L2X0_CACHE_SYNC);
+#endif
cache_wait(base + L2X0_CACHE_SYNC, 1);
}