linux-kernel - [PATCH] arc: Keep D$ enabled to work-around incomplete SLC flushing

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Date:   Fri, 17 Mar 2017 16:00:37 +0300
From:   Alexey Brodkin <Alexey.Brodkin@...opsys.com>
To:     Eugeniy.Paltsev@...opsys.com
Cc:     linux-snps-arc@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] arc: Keep D$ enabled to work-around incomplete SLC flushing

As reported in STAR 9001165532 if D$ is disabled SLC is not flushed
correctly which leads to loses of some data that were set before the flush.
That causes unexpected behavior after the flush.

For now just keep D$ enabled, only flush-invalidate it before IOC setup.

Signed-off-by: Alexey Brodkin <abrodkin@...opsys.com>
---
 arch/arc/mm/cache.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index d408fa21a07c..e0e83543e777 100644
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -997,8 +997,8 @@ noinline void __init arc_ioc_setup(void)
 {
 	unsigned int ap_sz;
 
-	/* Flush + invalidate + disable L1 dcache */
-	__dc_disable();
+	/* Flush + invalidate L1 dcache */
+	__dc_entire_op(OP_FLUSH_N_INV);
 
 	/* Flush + invalidate SLC */
 	if (read_aux_reg(ARC_REG_SLC_BCR))
-- 
2.7.4