From: Penny Zheng <penny.zheng@amd.com>
amd-cppc on active mode bypasses the scaling governor layer, and
provides its own P-state selection algorithms in hardware. Consequently,
when it is used, the driver's -> setpolicy() callback is invoked
to register per-CPU utilization update callbacks, not the ->target()
callback.
So, only when cpufreq_driver.setpolicy is NULL, we need to deliberately
set old gov as NULL to trigger the according gov starting.
Signed-off-by: Penny Zheng <Penny.Zheng@amd.com>
---
v1 -> v2:
- Change condition check to .setpolicy being NULL
---
xen/drivers/cpufreq/cpufreq.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/xen/drivers/cpufreq/cpufreq.c b/xen/drivers/cpufreq/cpufreq.c
index c0c6dc4c42..860ae32c8a 100644
--- a/xen/drivers/cpufreq/cpufreq.c
+++ b/xen/drivers/cpufreq/cpufreq.c
@@ -317,7 +317,13 @@ int cpufreq_add_cpu(unsigned int cpu)
if (hw_all || (cpumask_weight(cpufreq_dom->map) ==
perf->domain_info.num_processors)) {
memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
- policy->governor = NULL;
+
+ /*
+ * Only when cpufreq_driver.setpolicy == NULL, we need to deliberately
+ * set old gov as NULL to trigger the according gov starting.
+ */
+ if ( cpufreq_driver.setpolicy == NULL )
+ policy->governor = NULL;
cpufreq_cmdline_common_para(&new_policy);
--
2.34.1