Re: [PATCH v4] x86, sched: Fix the AMD CPPC maximum perf on some specific generations

On Sun, 25 Apr 2021, Huang Rui wrote:

Some AMD Ryzen generations has different calculation method on maximum perf. 255 is not for all asics, some specific generations should use 166 as the maximum perf. Otherwise, it will report incorrect frequency value like below:

The commit message says '255', but the code:

--- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1170,3 +1170,19 @@ void set_dr_addr_mask(unsigned long mask, int dr) break; } }

+u32 amd_get_highest_perf(void) +{

• struct cpuinfo_x86 *c = &boot_cpu_data;
• if (c->x86 == 0x17 && ((c->x86_model >= 0x30 && c->x86_model < 0x40) ||

• 	       (c->x86_model >= 0x70 && c->x86_model < 0x80)))
  

•    return 166;
  

• if (c->x86 == 0x19 && ((c->x86_model >= 0x20 && c->x86_model < 0x30) ||

• 	       (c->x86_model >= 0x40 && c->x86_model < 0x70)))
  

•    return 166;
  

• return 225;

+}

says 225? This is probably a typo? In any case they are out of sync.

Alexander