Clearing bit 22 in the PL310 Auxiliary Control register (shared
attribute override enable) has the side effect of transforming Normal
Shared Non-cacheable reads into Cacheable no-allocate reads.
Coherent DMA buffers in Linux always have a Cacheable alias via the
kernel linear mapping and the processor can speculatively load cache
lines into the PL310 controller. With bit 22 cleared, Non-cacheable
reads would unexpectedly hit such cache lines leading to buffer
corruption
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
Tested-by: Nishanth Menon <nm@xxxxxx>
---
arch/arm/mach-omap2/omap4-common.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mach-omap2/omap4-common.c b/arch/arm/mach-omap2/omap4-common.c
index b3cea78..2006da1 100644
--- a/arch/arm/mach-omap2/omap4-common.c
+++ b/arch/arm/mach-omap2/omap4-common.c
@@ -80,6 +80,7 @@ static int __init omap_l2_cache_init(void)
aux_ctrl |= 0x2 << L2X0_AUX_CTRL_WAY_SIZE_SHIFT;
} else {
aux_ctrl |= ((0x3 << L2X0_AUX_CTRL_WAY_SIZE_SHIFT) |
+ (1 << L2X0_AUX_CTRL_SHARE_OVERRIDE_SHIFT) |
(1 << L2X0_AUX_CTRL_DATA_PREFETCH_SHIFT) |
(1 << L2X0_AUX_CTRL_INSTR_PREFETCH_SHIFT));
}
--
1.6.0.4
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