irqchip/gic: Don't unnecessarily write the IRQ configuration

If the interrupt configuration matches the current configuration, then
don't bother writing the configuration again.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/drivers/irqchip/irq-gic-common.c b/drivers/irqchip/irq-gic-common.c
index f174ce0ca36115dc36feec5f047af7bf402e180a..ffff5a45f1e3008c7b96c1e4e4de39449dc8a93f 100644 (file)
--- a/drivers/irqchip/irq-gic-common.c
+++ b/drivers/irqchip/irq-gic-common.c
@@ -50,13 +50,17 @@ int gic_configure_irq(unsigned int irq, unsigned int type,
        else if (type & IRQ_TYPE_EDGE_BOTH)
                val |= confmask;
 
+       /* If the current configuration is the same, then we are done */
+       if (val == oldval)
+               return 0;
+
        /*
         * Write back the new configuration, and possibly re-enable
-        * the interrupt. If we tried to write a new configuration and failed,
+        * the interrupt. If we fail to write a new configuration,
         * return an error.
         */
        writel_relaxed(val, base + GIC_DIST_CONFIG + confoff);
-       if (readl_relaxed(base + GIC_DIST_CONFIG + confoff) != val && val != oldval)
+       if (readl_relaxed(base + GIC_DIST_CONFIG + confoff) != val)
                ret = -EINVAL;
 
        if (sync_access)