| Message ID | 20240506075816.1325303-1-liwei728@huawei.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | [v2] cpufreq/cppc: fix perf_to_khz/khz_to_perf conversion exception | expand |
On 06-05-24, 15:58, liwei wrote: > When the nominal_freq recorded by the kernel is equal to the lowest_freq, > and the frequency adjustment operation is triggered externally, there is > a logic error in cppc_perf_to_khz()/cppc_khz_to_perf(), resulting in perf > and khz conversion errors. > > Fix this by adding the branch processing logic when nominal_freq is equal > to lowest_freq. > > Fixes: ec1c7ad47664 ("cpufreq: CPPC: Fix performance/frequency conversion") > Signed-off-by: liwei <liwei728@huawei.com> > --- > v2: > - Fix similar issue in cppc_khz_to_perf() > > drivers/acpi/cppc_acpi.c | 22 +++++++++++++++++----- > 1 file changed, 17 insertions(+), 5 deletions(-) Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
kindly ping 在 2024/5/20 15:25, Viresh Kumar 写道: > On 06-05-24, 15:58, liwei wrote: >> When the nominal_freq recorded by the kernel is equal to the lowest_freq, >> and the frequency adjustment operation is triggered externally, there is >> a logic error in cppc_perf_to_khz()/cppc_khz_to_perf(), resulting in perf >> and khz conversion errors. >> >> Fix this by adding the branch processing logic when nominal_freq is equal >> to lowest_freq. >> >> Fixes: ec1c7ad47664 ("cpufreq: CPPC: Fix performance/frequency conversion") >> Signed-off-by: liwei <liwei728@huawei.com> >> --- >> v2: >> - Fix similar issue in cppc_khz_to_perf() >> >> drivers/acpi/cppc_acpi.c | 22 +++++++++++++++++----- >> 1 file changed, 17 insertions(+), 5 deletions(-) > > Acked-by: Viresh Kumar <viresh.kumar@linaro.org> >
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index a40b6f3946ef..e3a0d6b46b24 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -1869,9 +1869,15 @@ unsigned int cppc_perf_to_khz(struct cppc_perf_caps *caps, unsigned int perf) u64 mul, div; if (caps->lowest_freq && caps->nominal_freq) { - mul = caps->nominal_freq - caps->lowest_freq; + /* Avoid special case when nominal_freq is equal to lowest_freq */ + if (caps->lowest_freq == caps->nominal_freq) { + mul = caps->nominal_freq; + div = caps->nominal_perf; + } else { + mul = caps->nominal_freq - caps->lowest_freq; + div = caps->nominal_perf - caps->lowest_perf; + } mul *= KHZ_PER_MHZ; - div = caps->nominal_perf - caps->lowest_perf; offset = caps->nominal_freq * KHZ_PER_MHZ - div64_u64(caps->nominal_perf * mul, div); } else { @@ -1892,11 +1898,17 @@ unsigned int cppc_khz_to_perf(struct cppc_perf_caps *caps, unsigned int freq) { s64 retval, offset = 0; static u64 max_khz; - u64 mul, div; + u64 mul, div; if (caps->lowest_freq && caps->nominal_freq) { - mul = caps->nominal_perf - caps->lowest_perf; - div = caps->nominal_freq - caps->lowest_freq; + /* Avoid special case when nominal_freq is equal to lowest_freq */ + if (caps->lowest_freq == caps->nominal_freq) { + mul = caps->nominal_perf; + div = caps->nominal_freq; + } else { + mul = caps->nominal_perf - caps->lowest_perf; + div = caps->nominal_freq - caps->lowest_freq; + } /* * We don't need to convert to kHz for computing offset and can * directly use nominal_freq and lowest_freq as the div64_u64
When the nominal_freq recorded by the kernel is equal to the lowest_freq, and the frequency adjustment operation is triggered externally, there is a logic error in cppc_perf_to_khz()/cppc_khz_to_perf(), resulting in perf and khz conversion errors. Fix this by adding the branch processing logic when nominal_freq is equal to lowest_freq. Fixes: ec1c7ad47664 ("cpufreq: CPPC: Fix performance/frequency conversion") Signed-off-by: liwei <liwei728@huawei.com> --- v2: - Fix similar issue in cppc_khz_to_perf() drivers/acpi/cppc_acpi.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-)