ARM: 6294/1: etm: do a dummy read from OSSRR during initialization
The first read from ETM OS save and restore register after the power
down bit deassertion returns garbage.
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c
index 9e9db63..56418f9 100644
--- a/arch/arm/kernel/etm.c
+++ b/arch/arm/kernel/etm.c
@@ -543,7 +543,9 @@
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);