[PATCH 2/2] cpufreq: CPPC: Fix error handling in cppc_scale_freq_workfn()

[Bowen Yu <yubowen8@huawei.com>]

From: Jie Zhan <zhanjie9@hisilicon.com>

Perf counters could be 0 if the cpu is in a low-power idle state. Just try
it again next time and update the frequency scale when the cpu is active
and perf counters successfully return.

Also, remove the FIE source on an actual failure.

Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com>
---
 drivers/cpufreq/cppc_cpufreq.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 904006027df2..e95844d3d366 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -78,12 +78,23 @@ static void cppc_scale_freq_workfn(struct kthread_work *work)
 	struct cppc_cpudata *cpu_data;
 	unsigned long local_freq_scale;
 	u64 perf;
+	int ret;
 
 	cppc_fi = container_of(work, struct cppc_freq_invariance, work);
 	cpu_data = cppc_fi->cpu_data;
 
-	if (cppc_get_perf_ctrs(cppc_fi->cpu, &fb_ctrs)) {
+	ret = cppc_get_perf_ctrs(cppc_fi->cpu, &fb_ctrs);
+	/*
+	 * Perf counters could be 0 if the cpu is in a low-power idle state.
+	 * Just try it again next time.
+	 */
+	if (ret == -EFAULT)
+		return;
+
+	if (ret) {
 		pr_warn("%s: failed to read perf counters\n", __func__);
+		topology_clear_scale_freq_source(SCALE_FREQ_SOURCE_CPPC,
+						 cpu_data->shared_cpu_map);
 		return;
 	}
 
-- 
2.33.0