Can anyone take a look at this additional error handling of cppc_cpufreq?
Thanks!
Jie
On 21/08/2024 16:27, Jie Zhan wrote:
cc linux-arm-kernel
On 19/08/2024 11:51, Jie Zhan wrote:
The CPPC performance feedback counters could return 0 when the target
cpu
is in a deep idle state (e.g. powered off) and those counters are not
powered. cppc_cpufreq_get_rate() returns 0 in this case, triggering two
problems:
1. cpufreq_online() gets a false error and doesn't generate a cpufreq
policy, which happens in cpufreq_add_dev() when a new cpu device is
added.
2. 'cpuinfo_cur_freq' shows '<unknown>'
Don't take it as an error and return the frequency corresponding to the
desired perf when the feedback counters are 0.
Fixes: 6a4fec4f6d30 ("cpufreq: cppc: cppc_cpufreq_get_rate() returns
zero in all error cases.")
Signed-off-by: Jie Zhan <zhanjie9@xxxxxxxxxxxxx>
---
drivers/cpufreq/cppc_cpufreq.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/cpufreq/cppc_cpufreq.c
b/drivers/cpufreq/cppc_cpufreq.c
index bafa32dd375d..1c5eb12c1a5a 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -748,18 +748,25 @@ static unsigned int
cppc_cpufreq_get_rate(unsigned int cpu)
ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t0);
if (ret)
- return 0;
+ goto out_err;
udelay(2); /* 2usec delay between sampling */
ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t1);
if (ret)
- return 0;
+ goto out_err;
delivered_perf = cppc_perf_from_fbctrs(cpu_data, &fb_ctrs_t0,
&fb_ctrs_t1);
return cppc_perf_to_khz(&cpu_data->perf_caps, delivered_perf);
+
+out_err:
+ if (ret == -EFAULT)
+ return cppc_perf_to_khz(&cpu_data->perf_caps,
+ cpu_data->perf_ctrls.desired_perf);
+
+ return 0;
}
static int cppc_cpufreq_set_boost(struct cpufreq_policy *policy,
int state)
