[PATCH 4/7] etm: do a dummy read from OSSRR during initialization

[Alexander Shishkin]

The first read from ETM OS save and restore register after the power
down bit deassertion returns garbage.

Signed-off-by: Alexander Shishkin <virtuoso@xxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 arch/arm/kernel/etm.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c
index d08062b..73b824a 100644
--- a/arch/arm/kernel/etm.c
+++ b/arch/arm/kernel/etm.c
@@ -558,7 +558,9 @@ static int __init etm_probe(struct amba_device *dev, struct amba_id *id)
 	t->etm_portsz = 1;
 
 	etm_unlock(t);
-	ret = etm_readl(t, ETMMR_PDSR);
+	(void)etm_readl(t, ETMMR_PDSR);
+	/* dummy first read */
+	(void)etm_readl(&tracer, ETMMR_OSSRR);
 
 	t->ncmppairs = etm_readl(t, ETMR_CONFCODE) & 0xf;
 	etm_writel(t, 0x440, ETMR_CTRL);
-- 
1.7.1

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