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>

diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index fc609550b7fa5385e01ce7f4f3c9dbc495477b0f..1c947b4c7f05e7018dcce7ef555fb3b0d7875279 100644 (file)
--- 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);