[PATCH v4 04/13] cpufreq: amd-pstate: prefetch cppc_req_cached value in amd_pstate_cpu_init()

Perry Yuan
2022-07-15T10:05:51Z

This cppc_req_cached valued should be prefetched during
amd_pstate_cpu_init call period, then the amd_pstate_update() will get
correct cached value before updating the perf to change the cpu perf
level.The cached values are read through MSR interface, so here use
shared_mem flag to check the registers are accessible

Also the core performance boost state will be initialized through
hardware configuration register

* shared_mem flag is used for the shared memory type CPPC implementation
which dose not support MSR interface operation

Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
---
drivers/cpufreq/amd-pstate.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 43e6df9f67f6..d8c4153dbe4f 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -92,6 +92,8 @@ struct amd_aperf_mperf {
* @prev: Last Aperf/Mperf/tsc count value read from register
* @freq: current cpu frequency value
* @boost_supported: check whether the Processor or SBIOS supports boost mode
+ * @precision_boost_off: the core performance boost disabled state
+ * @cppc_hw_conf_cached: the cached hardware configuration register
*
* The amd_cpudata is key private data for each CPU thread in AMD P-State, and
* represents all the attributes and goals that AMD P-State requests at runtime.
@@ -117,6 +119,7 @@ struct amd_cpudata {

u64 freq;
bool boost_supported;
+ bool precision_boost_off;
u64 cppc_hw_conf_cached;
};

@@ -547,12 +550,17 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
cpudata->lowest_nonlinear_freq = lowest_nonlinear_freq;

policy->driver_data = cpudata;
+ if (!shared_mem) {
+ ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_HW_CTL, &value);
+ if (ret)
+ return ret;
+ cpudata->precision_boost_off = value & AMD_CPPC_PRECISION_BOOST_ENABLED;

- ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_HW_CTL, &value);
- if (ret)
- return ret;
- WRITE_ONCE(cpudata->cppc_hw_conf_cached, value);
-
+ ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &value);
+ if (ret)
+ return ret;
+ WRITE_ONCE(cpudata->cppc_req_cached, value);
+ }
amd_pstate_boost_init(cpudata);

return 0;
--
2.32.0