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Shenoy" , Perry Yuan , "Rafael J. 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This, in turn, affected the maximum > frequency calculation, often resulting in reporting lower frequency > values. > > For example, on the Glinda SoC based board with the following > parameters: > > max_perf = 208 > nominal_perf = 100 > nominal_freq = 2600 MHz > > The Linux kernel previously calculated the frequency as: > freq = ((max_perf * 1024 / nominal_perf) * nominal_freq) / 1024 > freq = 5405 MHz // Integer arithmetic. > > With the updated formula: > freq = (max_perf * nominal_freq) / nominal_perf > freq = 5408 MHz > > This change ensures more accurate frequency calculations by eliminating > unnecessary shifts and divisions, thereby improving precision. > > Signed-off-by: Naresh Solanki > > Changes in V3: > 1. Also update the same for lowest_nonlinear_freq > > Changes in V2: > 1. Rebase on superm1.git/linux-next branch > --- Reviewed-by: Mario Limonciello BTW - Over the holiday I added this to my bleeding-edge branch [1] and have done testing with it. I will be including it in my next 6.14 PR, thanks! [1] https://git.kernel.org/pub/scm/linux/kernel/git/superm1/linux.git/commit/?h=bleeding-edge&id=857a61c2ce74e30fc3b10bc89d68ddd8d05b188c > drivers/cpufreq/amd-pstate.c | 13 ++++--------- > 1 file changed, 4 insertions(+), 9 deletions(-) > > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c > index d7b1de97727a..6f6f3220ffe4 100644 > --- a/drivers/cpufreq/amd-pstate.c > +++ b/drivers/cpufreq/amd-pstate.c > @@ -908,9 +908,8 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata) > { > int ret; > u32 min_freq, max_freq; > - u32 nominal_perf, nominal_freq; > + u32 highest_perf, nominal_perf, nominal_freq; > u32 lowest_nonlinear_perf, lowest_nonlinear_freq; > - u32 boost_ratio, lowest_nonlinear_ratio; > struct cppc_perf_caps cppc_perf; > > ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf); > @@ -927,16 +926,12 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata) > else > nominal_freq = cppc_perf.nominal_freq; > > + highest_perf = READ_ONCE(cpudata->highest_perf); > nominal_perf = READ_ONCE(cpudata->nominal_perf); > - > - boost_ratio = div_u64(cpudata->highest_perf << SCHED_CAPACITY_SHIFT, nominal_perf); > - max_freq = (nominal_freq * boost_ratio >> SCHED_CAPACITY_SHIFT); > + max_freq = div_u64((u64)highest_perf * nominal_freq, nominal_perf); > > lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf); > - lowest_nonlinear_ratio = div_u64(lowest_nonlinear_perf << SCHED_CAPACITY_SHIFT, > - nominal_perf); > - lowest_nonlinear_freq = (nominal_freq * lowest_nonlinear_ratio >> SCHED_CAPACITY_SHIFT); > - > + lowest_nonlinear_freq = div_u64((u64)nominal_freq * lowest_nonlinear_perf, nominal_perf); > WRITE_ONCE(cpudata->min_freq, min_freq * 1000); > WRITE_ONCE(cpudata->lowest_nonlinear_freq, lowest_nonlinear_freq * 1000); > WRITE_ONCE(cpudata->nominal_freq, nominal_freq * 1000);