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

Alexander Shishkin
2010-07-25T17:11:37Z

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

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
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