| Message ID | 20240430101227.2133288-1-liwei728@huawei.com |
|---|---|
| State | New |
| Headers | show |
| Series | cpufreq/cppc: fix perf_to_khz conversion exception | expand |
Hello Liwei, Thanks for the fix. I think there might be a similar issue in cppc_khz_to_perf(), Regards, Pierre On 4/30/24 12:12, liwei wrote: > When the nominal_freq recorded by the kernel is equal to lowest_freq and > the frequency reduction operation is triggered externally, there is a > conversion logic error in cppc_perf_to_khz(), causing the kernel to be > unable to feedback the true frequency. > > 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> > --- > drivers/acpi/cppc_acpi.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c > index a40b6f3946ef..92aac6974e0e 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 the 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 {
Hello Pierre, Thanks for your reminder. 在 2024/5/3 15:42, Pierre Gondois 写道: > Hello Liwei, > > Thanks for the fix. I think there might be a similar issue > in cppc_khz_to_perf(), > > Regards, > Pierre > cppc_khz_to_perf() also has similar issue, I will modify the patch again. Liwei > On 4/30/24 12:12, liwei wrote: >> When the nominal_freq recorded by the kernel is equal to lowest_freq and >> the frequency reduction operation is triggered externally, there is a >> conversion logic error in cppc_perf_to_khz(), causing the kernel to be >> unable to feedback the true frequency. >> >> 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> >> --- >> drivers/acpi/cppc_acpi.c | 10 ++++++++-- >> 1 file changed, 8 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c >> index a40b6f3946ef..92aac6974e0e 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 the 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 {
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index a40b6f3946ef..92aac6974e0e 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 the 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 {
When the nominal_freq recorded by the kernel is equal to lowest_freq and the frequency reduction operation is triggered externally, there is a conversion logic error in cppc_perf_to_khz(), causing the kernel to be unable to feedback the true frequency. 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> --- drivers/acpi/cppc_acpi.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)