@@ -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(-)