ARM: cpuidle: Remove overzealous error logging

CPUidle back-end operations are not implemented in some platforms
but this should not be considered an error serious enough to be
logged. Check the arm_cpuidle_init() return value to detect whether
the failure must be reported or not in the kernel log and do
not log it if the platform does not support CPUidle operations.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Will Deacon <will@kernel.org>

drivers/cpuidle/cpuidle-arm.c

@@ -105,10 +105,16 @@ static int __init arm_idle_init_cpu(int cpu)
 	ret = arm_cpuidle_init(cpu);
 
 	/*
-	 * Allow the initialization to continue for other CPUs, if the reported
-	 * failure is a HW misconfiguration/breakage (-ENXIO).
+	 * Allow the initialization to continue for other CPUs, if the
+	 * reported failure is a HW misconfiguration/breakage (-ENXIO).
+	 *
+	 * Some platforms do not support idle operations
+	 * (arm_cpuidle_init() returning -EOPNOTSUPP), we should
+	 * not flag this case as an error, it is a valid
+	 * configuration.
 	 */
 	if (ret) {
+		if (ret != -EOPNOTSUPP)
 			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
 		ret = ret == -ENXIO ? 0 : ret;
 		goto out_kfree_drv;