Re: [PATCH] cpufreq/amd-pstate: Supply nominal/lowest freq for TRX40-based motherboards

[Mario Limonciello <mario.limonciello@amd.com>]

Kyle,

Can you please confirm more about your system?  System Model, vendor, 
BIOS version, BIOS vendor, CPU model.

Thanks,

On 10/7/26 10:04, Kyle Gospodnetich wrote:
> Yes this does appear to be the same problem, thank you!
> 
> -------- Original Message --------
> On Wednesday, 10/07/26 at 07:56 Mario Limonciello <mario.limonciello@amd.com> wrote:
> + Kyle
> 
> Kyle,
> 
> By chance is this the same system that you were talking to me about offline?
> 
> 
> 
> On 10/7/26 09:41, Giovanni Gherdovich wrote:
>> Some motherboard based on the TRX40 chipset has been reported to ship
>> firmware lacking lowest and nominal frequency values in the
>> _CPC ACPI package. That is, it supports CPPC V2 but not CPPC V3.
>> Firmware updates aren't available.
> 
> Can you please add more information about the vendor/model of the MB, etc?
>>
>> amd-pstate requires explicit knowledge of nominal frequency, so it
>> can't load on this hardware. The driver already has a mechanism (the
>> so-called "quirks") to accommodate for missing nominal freq in ACPI
>> tables, so here we use it to match against CPU family, model, core
>> count, and BIOS version.
> 
> Yeah; it's intended for this specific case of really old hardware that
> the BIOS isn't going to fix it.
> 
> I don't understand why core count matters though.
> 
>>
>> Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
>> ---
>>    drivers/cpufreq/amd-pstate.c | 31 +++++++++++++++++++++++++++++++
>>    1 file changed, 31 insertions(+)
>>
>> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
>> index 8bfd46d60843..532ff16dd076 100644
>> --- a/drivers/cpufreq/amd-pstate.c
>> +++ b/drivers/cpufreq/amd-pstate.c
>> @@ -145,6 +145,11 @@ static struct quirk_entry quirk_amd_7k62 = {
>>    	.lowest_freq = 550,
>>    };
>>
>> +static struct quirk_entry quirk_amd_ryzen_threadripper_3000_24c = {
>> +	.nominal_freq = 3800,
>> +	.lowest_freq = 550,
>> +};
>> +
>>    static inline u8 freq_to_perf(union perf_cached perf, u32 nominal_freq, unsigned int freq_val)
>>    {
>>    	u32 perf_val = DIV_ROUND_UP_ULL((u64)freq_val * perf.nominal_perf, nominal_freq);
>> @@ -174,6 +179,22 @@ static int __init dmi_matched_7k62_bios_bug(const struct dmi_system_id *dmi)
>>    	return 0;
>>    }
>>
>> +static int __init dmi_matched_trx40_bios_bug(const struct dmi_system_id *dmi)
>> +{
>> +	/**
>> +	 * Match the Ryzen Threadripper 3000 series, 24-core SKU, sTRX4 socket / TRX40 chipset.
>> +	 */
>> +	if (boot_cpu_data.x86 == 0x17 &&
>> +	    boot_cpu_data.x86_model >= 0x30 && boot_cpu_data.x86_model <= 0x3F &&
>> +	    topology_num_cores_per_package() == 24) {
> 
> Does the number of cores actually matter?  Do you mean to say if you
> swap the CPU to another part CPPC works?
> 
>> +		quirks = dmi->driver_data;
>> +		pr_info("Overriding nominal and lowest frequencies for %s\n", dmi->ident);
> 
> The BIOS bug specifically is lack of values, not invalid values, right?
> Just want to make sure I'm following this right.
> 
>> +		return 1;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>    static const struct dmi_system_id amd_pstate_quirks_table[] __initconst = {
>>    	{
>>    		.callback = dmi_matched_7k62_bios_bug,
>> @@ -184,6 +205,16 @@ static const struct dmi_system_id amd_pstate_quirks_table[] __initconst = {
>>    		},
>>    		.driver_data = &quirk_amd_7k62,
>>    	},
>> +	{
>> +		.callback = dmi_matched_trx40_bios_bug,
>> +		.ident = "AMD Ryzen Threadripper 3000",
>> +		.matches = {
>> +			DMI_MATCH(DMI_BIOS_VENDOR,  "American Megatrends International"),
>> +			DMI_MATCH(DMI_BIOS_VERSION, "2.80"),
>> +			DMI_MATCH(DMI_BIOS_DATE,    "05/17/2022"),
>> +		},
>> +		.driver_data = &quirk_amd_ryzen_threadripper_3000_24c,
>> +	},
>>    	{}
>>    };
>>    MODULE_DEVICE_TABLE(dmi, amd_pstate_quirks_table);
>