ARM: l2c: only write the auxiliary control register if required

Avoid unnecessary writes to the auxiliary control register if the
register already contains the required value.  This allows us to
avoid invoking the platforms secure monitor code unnecessarily.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index fc609550b7fa..1c947b4c7f05 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -92,7 +92,9 @@ static void l2c_enable(void __iomem *base, u32 aux, unsigned num_lock)
 {
         unsigned long flags;
 
-        writel_relaxed(aux, base + L2X0_AUX_CTRL);
+        /* Only write the aux register if it needs changing */
+        if (readl_relaxed(base + L2X0_AUX_CTRL) != aux)
+                writel_relaxed(aux, base + L2X0_AUX_CTRL);
 
         l2c_unlock(base, num_lock);