cpufreq: cppc: cppc_cpufreq_get_rate() returns zero in all error cases.

The cpufreq framework used to use the zero of return value to reflect
the cppc_cpufreq_get_rate() had failed to get current frequecy and treat
all positive integer to be succeed. Since cppc_get_perf_ctrs() returns a
negative integer in error case, so it is better to convert the value to
zero as the return value of cppc_cpufreq_get_rate().

Signed-off-by: Liao Chang <liaochang1@huawei.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: Liao Chang

drivers/cpufreq/cppc_cpufreq.c

@@ -849,13 +849,13 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpu)
 
 	ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t0);
 	if (ret)
-		return ret;
+		return 0;
 
 	udelay(2); /* 2usec delay between sampling */
 
 	ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t1);
 	if (ret)
-		return ret;
+		return 0;
 
 	delivered_perf = cppc_perf_from_fbctrs(cpu_data, &fb_ctrs_t0,
 					       &fb_ctrs_t1);

include/linux/cpufreq.h

@@ -370,7 +370,7 @@ struct cpufreq_driver {
 	int		(*target_intermediate)(struct cpufreq_policy *policy,
 					       unsigned int index);
 
-	/* should be defined, if possible */
+	/* should be defined, if possible, return 0 on error */
 	unsigned int	(*get)(unsigned int cpu);
 
 	/* Called to update policy limits on firmware notifications. */