Messages in this thread | | | From | Punit Agrawal <> | Subject | Re: [PATCH v5 4/7] cpufreq: amd_pstate: fix wrong lowest perf fetch | Date | Thu, 01 Sep 2022 15:58:50 +0100 |
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"Yuan, Perry" <Perry.Yuan@amd.com> writes:
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>> Perry Yuan <Perry.Yuan@amd.com> writes: >> >> > Fix the wrong lowest perf value reading which is used for new des_perf >> > calculation by governor requested, the incorrect min_perf will get >> > incorrect des_perf to be set , that will cause the system frequency >> > changing unexpectedly. >> > >> > Reviewed-by: Huang Rui <ray.huang@amd.com> >> > Acked-by: Viresh Kumar <viresh.kumar@linaro.org> >> > Signed-off-by: Perry Yuan <Perry.Yuan@amd.com> >> > Signed-off-by: Su Jinzhou <jinzhou.su@amd.com> >> > --- >> > drivers/cpufreq/amd-pstate.c | 2 +- >> > 1 file changed, 1 insertion(+), 1 deletion(-) >> > >> > diff --git a/drivers/cpufreq/amd-pstate.c >> > b/drivers/cpufreq/amd-pstate.c index 5cdef6638681..183cdd4ba00e 100644 >> > --- a/drivers/cpufreq/amd-pstate.c >> > +++ b/drivers/cpufreq/amd-pstate.c >> > @@ -307,7 +307,7 @@ static int amd_pstate_target(struct cpufreq_policy >> *policy, >> > return -ENODEV; >> > >> > cap_perf = READ_ONCE(cpudata->highest_perf); >> > - min_perf = READ_ONCE(cpudata->lowest_nonlinear_perf); >> > + min_perf = READ_ONCE(cpudata->lowest_perf); >> > max_perf = cap_perf; >> > >> > freqs.old = policy->cur; >> >> This looks to be a pretty big change (lowest nonlinear vs lowest). Does the patch >> need to be backported to older kernels? > > The patch fixes the min perf initial value, the correct min perf is lowest_perf which is captured through MSR_AMD_CPPC_CAP1 register or the cppc_get_perf_caps(). > Yes, the patch will need to be backported to other kernel branch as issue fix.
Great, thanks for confirming!
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