common/octeontx2: fix to prevent STP instruction fissure
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Commit Message
From: Jerin Jacob <jerinj@marvell.com>
OTX2 AP core can sometimes fissure STP instructions when it is more
optimal to send such writes into the pipeline as 2 separate
instructions. However registers should be excluded from such
optimization. This commit ensures that no CSR write is ever fissured
by introducing zero cost workaround by setting STP pre-index by zero to
make sure OTX2 AP core prevent fissure.
Fixes: 8a4f835971f5 ("common/octeontx2: add IO handling APIs")
Signed-off-by: Jerin Jacob <jerinj@marvell.com>
---
drivers/common/octeontx2/otx2_io_arm64.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Comments
26/07/2019 07:24, jerinj@marvell.com:
> From: Jerin Jacob <jerinj@marvell.com>
>
> OTX2 AP core can sometimes fissure STP instructions when it is more
> optimal to send such writes into the pipeline as 2 separate
> instructions. However registers should be excluded from such
> optimization. This commit ensures that no CSR write is ever fissured
> by introducing zero cost workaround by setting STP pre-index by zero to
> make sure OTX2 AP core prevent fissure.
>
> Fixes: 8a4f835971f5 ("common/octeontx2: add IO handling APIs")
>
> Signed-off-by: Jerin Jacob <jerinj@marvell.com>
Applied, thanks
@@ -14,7 +14,7 @@
#define otx2_store_pair(val0, val1, addr) ({ \
asm volatile( \
- "stp %x[x0], %x[x1], [%x[p1]]" \
+ "stp %x[x0], %x[x1], [%x[p1],#0]!" \
::[x0]"r"(val0), [x1]"r"(val1), [p1]"r"(addr) \
); })