* Huang Rui [off-list ref] wrote:

On Thu, May 13, 2021 at 06:59:02AM +0800, Ingo Molnar wrote:

quoted

* Alexander Monakov [off-list ref] wrote:

quoted

On Sun, 25 Apr 2021, Huang Rui wrote:

quoted

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:

quoted

--- 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

Ugh - that's indeed a good question ...

Ah sorry! It's my typo. It should be 255 (confirmed in the ucode).

Alexander, thanks a lot to catch this!

Ingo, would you mind to update it from 225 -> 255 while you apply this
patch or let me know if you want me to send v5?

No need to send v5, done!

I have a system that appears to be affected by this bug:

  kepler:~> lscpu | grep -i mhz
  CPU MHz:                         4000.000
  CPU max MHz:                     7140.6250
  CPU min MHz:                     2200.0000

So I should be able to confirm after a reboot.

Thanks,

	Ingo