[PATCH] cpufreq/amd-pstate: Do not fail init when auto_sel cannot be written

[PATCH] cpufreq/amd-pstate: Do not fail init when auto_sel cannot be written

[Wentao Guan]

Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
mode on shared memory systems"), shmem_init_perf() programs
AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.

On platforms implementing CPPC v2 and below, _CPC reports Autonomous
Selection Enable as a plain integer rather than as a register descriptor.
Such a field is a read-only capability flag: cppc_get_reg_val() reads it
back successfully (the firmware reports it as enabled), while
cppc_set_reg_val() rejects the write with -EOPNOTSUPP because the entry is
not an ACPI_TYPE_BUFFER.

shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
fails, cpufreq_register_driver() ends up with an empty policy list and
returns -ENODEV, and amd-pstate refuses to load at all:

  amd_pstate: failed to set auto_sel, ret: -95
  amd_pstate: Failed to initialize CPU 0: -95
  ...
  amd_pstate: failed to register with return -19

Failing to write auto_sel is not fatal: the register is either already
enabled, as reported by the cppc_get_auto_sel() call right above, or not
writable at all, and active mode worked in both cases before the offending
commit.  Downgrade the failure to a warning and let initialization
continue, matching how the cppc_get_auto_sel() failure is handled.

Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems")
Cc: stable@vger.kernel.org
Tested-by: LFRon <ronforever@outlook.com>
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
---
 drivers/cpufreq/amd-pstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 80d99ba1902c9..3657c5cccd4d8 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -538,5 +538,5 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
 	if (ret)
 		pr_warn("failed to set auto_sel, ret: %d\n", ret);
 
-	return ret;
+	return 0;
 }

Re: [PATCH] cpufreq/amd-pstate: Do not fail init when auto_sel cannot be written

[K Prateek Nayak]

Hello Wentao,

On 9/18/2026 10:12 AM, Wentao Guan wrote:
> Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
> mode on shared memory systems"), shmem_init_perf() programs
> AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.
> 
> On platforms implementing CPPC v2 and below, _CPC reports Autonomous
> Selection Enable as a plain integer rather than as a register descriptor.
> Such a field is a read-only capability flag: cppc_get_reg_val() reads it
> back successfully (the firmware reports it as enabled), while
> cppc_set_reg_val() rejects the write with -EOPNOTSUPP because the entry is
> not an ACPI_TYPE_BUFFER.

Ah! So it is one of those platforms that fall into:

    Platforms that exclusively support Autonomous Selection must populate
    this field as an Integer with a value of 1.

as per the ACPI spec.

> 
> shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
> fails, cpufreq_register_driver() ends up with an empty policy list and
> returns -ENODEV, and amd-pstate refuses to load at all:
> 
>   amd_pstate: failed to set auto_sel, ret: -95
>   amd_pstate: Failed to initialize CPU 0: -95
>   ...
>   amd_pstate: failed to register with return -19
> 
> Failing to write auto_sel is not fatal: the register is either already
> enabled, as reported by the cppc_get_auto_sel() call right above, or not
> writable at all, and active mode worked in both cases before the offending
> commit.  Downgrade the failure to a warning and let initialization
> continue, matching how the cppc_get_auto_sel() failure is handled.

Can't we just skip cppc_set_auto_sel() if the auto_sel is already at
the desired value? Something like:

  (Completely untested)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index d4ff8b228f86..ed540da818ef 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -524,6 +524,9 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
 		return 0;
 	}
 
+	if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel)
+		return 0;
+
 	ret = cppc_set_auto_sel(cpudata->cpu,
 			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
 
---

That way we fail for passive mode switch which will operate under
incorrectly assumptions since these platform only supports autonomous
modes.

Thoughts?

> 
> Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems")
> Cc: stable@vger.kernel.org
> Tested-by: LFRon <ronforever@outlook.com>
> Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
> ---
>  drivers/cpufreq/amd-pstate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 80d99ba1902c9..3657c5cccd4d8 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -538,5 +538,5 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
>         if (ret)
>                 pr_warn("failed to set auto_sel, ret: %d\n", ret);
> 
> -       return ret;
> +       return 0;
>  }

-- 
Thanks and Regards,
Prateek

Re: [PATCH] cpufreq/amd-pstate: Do not fail init when auto_sel cannot be written

[Wentao Guan]

Hi,

> On 9/18/2026 10:12 AM, Wentao Guan wrote:
> > Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
> > mode on shared memory systems"), shmem_init_perf() programs
> > AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.
> >
> > On platforms implementing CPPC v2 and below, _CPC reports Autonomous
> > Selection Enable as a plain integer rather than as a register descriptor.
> > Such a field is a read-only capability flag: cppc_get_reg_val() reads it
> > back successfully (the firmware reports it as enabled), while
> > cppc_set_reg_val() rejects the write with -EOPNOTSUPP because the entry is
> > not an ACPI_TYPE_BUFFER.
> 
> Ah! So it is one of those platforms that fall into:
> 
>     Platforms that exclusively support Autonomous Selection must populate
>     this field as an Integer with a value of 1.
> 
> as per the ACPI spec.
> 
> >
> > shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
> > fails, cpufreq_register_driver() ends up with an empty policy list and
> > returns -ENODEV, and amd-pstate refuses to load at all:
> >
> >   amd_pstate: failed to set auto_sel, ret: -95
> >   amd_pstate: Failed to initialize CPU 0: -95
> >   ...
> >   amd_pstate: failed to register with return -19
> >
> > Failing to write auto_sel is not fatal: the register is either already
> > enabled, as reported by the cppc_get_auto_sel() call right above, or not
> > writable at all, and active mode worked in both cases before the offending
> > commit.  Downgrade the failure to a warning and let initialization
> > continue, matching how the cppc_get_auto_sel() failure is handled.
> 
> Can't we just skip cppc_set_auto_sel() if the auto_sel is already at
> the desired value? Something like:
> 
>   (Completely untested)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index d4ff8b228f86..ed540da818ef 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -524,6 +524,9 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
>  		return 0;
>  	}
> 
> +	if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel)
> +		return 0;
> +
>  	ret = cppc_set_auto_sel(cpudata->cpu,
>  			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
> 
> ---
> 
> That way we fail for passive mode switch which will operate under
> incorrectly assumptions since these platform only supports autonomous
> modes.

> Thoughts?

Thanks for your review, full agree with your suggested patch.
I will send v2 after be tested later.

BRs
Wentao Guan

[PATCH v2] cpufreq/amd-pstate: Skip auto_sel write when it already matches the mode

[Wentao Guan]

Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
mode on shared memory systems"), shmem_init_perf() programs
AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.

Platforms that exclusively support autonomous selection report this field
as an Integer of 1, as required by the ACPI specification, instead of as a
register descriptor.  cppc_get_reg_val() reads such a field back
successfully, but cppc_set_reg_val() rejects the write with -EOPNOTSUPP
because the entry is not an ACPI_TYPE_BUFFER.

shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
fails, cpufreq_register_driver() ends up with an empty policy list and
returns -ENODEV, and amd-pstate refuses to load at all:

  amd_pstate: failed to set auto_sel, ret: -95
  amd_pstate: Failed to initialize CPU 0: -95
  ...
  amd_pstate: failed to register with return -19

Skip the write when the register already holds the value the requested mode
needs.  Active and guided mode are fixed on these platforms, which report
auto_sel as 1, while passive mode still fails to load on a platform that
cannot disable autonomous selection, exactly as it did before the
offending commit.

Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems")
Cc: stable@vger.kernel.org
Tested-by: LFRon <ronforever@outlook.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
---
changelog v2:
Accecpt and tested the K Prateek Nayak reviews.
v1 link:
https://lore.kernel.org/stable/20260918054808.48999-1-guanwentao@uniontech.com/#R
---
---
 drivers/cpufreq/amd-pstate.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 3a6b4b224a66d..91ec44f9fbb96 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -535,6 +535,9 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
 		return 0;
 	}
 
+	if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel)
+		return 0;
+
 	ret = cppc_set_auto_sel(cpudata->cpu,
 			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
 
-- 
2.30.2

Re: [PATCH v2] cpufreq/amd-pstate: Skip auto_sel write when it already matches the mode

[K Prateek Nayak]

Hello Wentao,

On 9/18/2026 12:38 PM, Wentao Guan wrote:
> Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
> mode on shared memory systems"), shmem_init_perf() programs
> AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.
> 
> Platforms that exclusively support autonomous selection report this field
> as an Integer of 1, as required by the ACPI specification, instead of as a
> register descriptor.  cppc_get_reg_val() reads such a field back
> successfully, but cppc_set_reg_val() rejects the write with -EOPNOTSUPP
> because the entry is not an ACPI_TYPE_BUFFER.
> 
> shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
> fails, cpufreq_register_driver() ends up with an empty policy list and
> returns -ENODEV, and amd-pstate refuses to load at all:
> 
>   amd_pstate: failed to set auto_sel, ret: -95
>   amd_pstate: Failed to initialize CPU 0: -95
>   ...
>   amd_pstate: failed to register with return -19
> 
> Skip the write when the register already holds the value the requested mode
> needs.  Active and guided mode are fixed on these platforms, which report
> auto_sel as 1, while passive mode still fails to load on a platform that
> cannot disable autonomous selection, exactly as it did before the
> offending commit.
> 
> Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems")
> Cc: stable@vger.kernel.org
> Tested-by: LFRon <ronforever@outlook.com>
> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>

You can flip that to:

Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>

You did all the hard work to find, debug, and test it!

> Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
> ---
> changelog v2:
> Accecpt and tested the K Prateek Nayak reviews.
> v1 link:
> https://lore.kernel.org/stable/20260918054808.48999-1-guanwentao@uniontech.com/#R
> ---
> ---
>  drivers/cpufreq/amd-pstate.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 3a6b4b224a66d..91ec44f9fbb96 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -535,6 +535,9 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
>  		return 0;
>  	}
>  
> +	if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel)
> +		return 0;
> +
>  	ret = cppc_set_auto_sel(cpudata->cpu,
>  			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);

nit. Now that we arrive here only to flip the autosel value,
you can just do:

    cppc_set_auto_sel(cpudata->cpu, !auto_sel)

... and remove that ternary op.

-- 
Thanks and Regards,
Prateek

[PATCH v3] cpufreq/amd-pstate: Skip auto_sel write when it already matches the mode

[Wentao Guan]

Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
mode on shared memory systems"), shmem_init_perf() programs
AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.

Platforms that exclusively support autonomous selection report this field
as an Integer of 1, as required by the ACPI specification, instead of as a
register descriptor.  cppc_get_reg_val() reads such a field back
successfully, but cppc_set_reg_val() rejects the write with -EOPNOTSUPP
because the entry is not an ACPI_TYPE_BUFFER.

shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
fails, cpufreq_register_driver() ends up with an empty policy list and
returns -ENODEV, and amd-pstate refuses to load at all:

  amd_pstate: failed to set auto_sel, ret: -95
  amd_pstate: Failed to initialize CPU 0: -95
  ...
  amd_pstate: failed to register with return -19

Skip the write when the register already holds the value the requested mode
needs.  Active and guided mode are fixed on these platforms, which report
auto_sel as 1, while passive mode still fails to load on a platform that
cannot disable autonomous selection, exactly as it did before the
offending commit.

Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems")
Cc: stable@vger.kernel.org
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: LFRon <ronforever@outlook.com>
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
---
changelog v3:
Include the K Prateek Nayak reviews to remove that ternary op base on current 
condition now have.  

v2 link: 
https://lore.kernel.org/stable/c3eb86bd-70a6-4bb2-8eff-b2a3c0817514@amd.com/#R
changelog v2:
Accecpt and tested the K Prateek Nayak reviews.
v1 link:
https://lore.kernel.org/stable/20260918054808.48999-1-guanwentao@uniontech.com/#R
---
---
 drivers/cpufreq/amd-pstate.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 80d99ba1902c9..2d1f5292d1738 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -532,8 +532,10 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
 		return 0;
 	}
 
-	ret = cppc_set_auto_sel(cpudata->cpu,
-			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
+	if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel)
+		return 0;
+
+	ret = cppc_set_auto_sel(cpudata->cpu, !auto_sel);
 
 	if (ret)
 		pr_warn("failed to set auto_sel, ret: %d\n", ret);
-- 
2.30.2

Re: [PATCH v3] cpufreq/amd-pstate: Skip auto_sel write when it already matches the mode

[Wentao Guan]

Hi,

> Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
> mode on shared memory systems"), shmem_init_perf() programs
> AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.
> 
> Platforms that exclusively support autonomous selection report this field
> as an Integer of 1, as required by the ACPI specification, instead of as a
> register descriptor.  cppc_get_reg_val() reads such a field back
> successfully, but cppc_set_reg_val() rejects the write with -EOPNOTSUPP
> because the entry is not an ACPI_TYPE_BUFFER.
> 
> shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
> fails, cpufreq_register_driver() ends up with an empty policy list and
> returns -ENODEV, and amd-pstate refuses to load at all:
> 
>   amd_pstate: failed to set auto_sel, ret: -95
>   amd_pstate: Failed to initialize CPU 0: -95
>   ...
>   amd_pstate: failed to register with return -19
> 
> Skip the write when the register already holds the value the requested mode
> needs.  Active and guided mode are fixed on these platforms, which report
> auto_sel as 1, while passive mode still fails to load on a platform that
> cannot disable autonomous selection, exactly as it did before the
> offending commit.
> 
> Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems")
> Cc: stable@vger.kernel.org
> Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
> Tested-by: LFRon <ronforever@outlook.com>
> Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
> ---
> changelog v3:
> Include the K Prateek Nayak reviews to remove that ternary op base on current
> condition now have.
> 
> v2 link:
> https://lore.kernel.org/stable/c3eb86bd-70a6-4bb2-8eff-b2a3c0817514@amd.com/#R
> changelog v2:
> Accecpt and tested the K Prateek Nayak reviews.
> v1 link:
> https://lore.kernel.org/stable/20260918054808.48999-1-guanwentao@uniontech.com/#R
> ---
> ---
> drivers/cpufreq/amd-pstate.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 80d99ba1902c9..2d1f5292d1738 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -532,8 +532,10 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
>  		return 0;
>  	}
> 
> -	ret = cppc_set_auto_sel(cpudata->cpu,
> -			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
> +	if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel)
> +		return 0;
> +
> +	ret = cppc_set_auto_sel(cpudata->cpu, !auto_sel);
> 
>  	if (ret)
>  		pr_warn("failed to set auto_sel, ret: %d\n", ret);
> --
> 2.30.2

Ping? Nearly a month passed, anything update?

BRs
Wentao Guan

Re: [PATCH v3] cpufreq/amd-pstate: Skip auto_sel write when it already matches the mode

[K Prateek Nayak]

Hello Wentao,

On 10/16/2026 11:21 AM, Wentao Guan wrote:
> Hi,
> 
>> Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
>> mode on shared memory systems"), shmem_init_perf() programs
>> AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.
>>
>> Platforms that exclusively support autonomous selection report this field
>> as an Integer of 1, as required by the ACPI specification, instead of as a
>> register descriptor.  cppc_get_reg_val() reads such a field back
>> successfully, but cppc_set_reg_val() rejects the write with -EOPNOTSUPP
>> because the entry is not an ACPI_TYPE_BUFFER.
>>
>> shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
>> fails, cpufreq_register_driver() ends up with an empty policy list and
>> returns -ENODEV, and amd-pstate refuses to load at all:
>>
>>   amd_pstate: failed to set auto_sel, ret: -95
>>   amd_pstate: Failed to initialize CPU 0: -95
>>   ...
>>   amd_pstate: failed to register with return -19
>>
>> Skip the write when the register already holds the value the requested mode
>> needs.  Active and guided mode are fixed on these platforms, which report
>> auto_sel as 1, while passive mode still fails to load on a platform that
>> cannot disable autonomous selection, exactly as it did before the
>> offending commit.
>>
>> Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems")
>> Cc: stable@vger.kernel.org
>> Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
>> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
>> Tested-by: LFRon <ronforever@outlook.com>
>> Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
>> ---
>> changelog v3:
>> Include the K Prateek Nayak reviews to remove that ternary op base on current
>> condition now have.
>>
>> v2 link:
>> https://lore.kernel.org/stable/c3eb86bd-70a6-4bb2-8eff-b2a3c0817514@amd.com/#R
>> changelog v2:
>> Accecpt and tested the K Prateek Nayak reviews.
>> v1 link:
>> https://lore.kernel.org/stable/20260918054808.48999-1-guanwentao@uniontech.com/#R
>> ---
>> ---
>> drivers/cpufreq/amd-pstate.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
>> index 80d99ba1902c9..2d1f5292d1738 100644
>> --- a/drivers/cpufreq/amd-pstate.c
>> +++ b/drivers/cpufreq/amd-pstate.c
>> @@ -532,8 +532,10 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
>>  		return 0;
>>  	}
>>
>> -	ret = cppc_set_auto_sel(cpudata->cpu,
>> -			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
>> +	if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel)
>> +		return 0;
>> +
>> +	ret = cppc_set_auto_sel(cpudata->cpu, !auto_sel);
>>
>>  	if (ret)
>>  		pr_warn("failed to set auto_sel, ret: %d\n", ret);
>> --
>> 2.30.2
> 
> Ping? Nearly a month passed, anything update?

On a similar issue here
https://lore.kernel.org/all/851316da-2cfa-4a22-947c-1838532d05cf@amd.com/
Mario had recently pointed out that this might be a BIOS issue on
systems that may have MSR interface but running an old BIOS that does
not advertise the CPUID bit.

Could you please share your system details here and check if you are
running the latest BIOS from your vendor?

-- 
Thanks and Regards,
Prateek

Re: [PATCH v3] cpufreq/amd-pstate: Skip auto_sel write when it already matches the mode

[Wentao Guan]

Hi,

>On 10/16/2026 11:21 AM, Wentao Guan wrote:
>> Hi,
>> 
>>> Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active
>>> mode on shared memory systems"), shmem_init_perf() programs
>>> AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode.
>>>
>>> Platforms that exclusively support autonomous selection report this field
>>> as an Integer of 1, as required by the ACPI specification, instead of as a
>>> register descriptor.  cppc_get_reg_val() reads such a field back
>>> successfully, but cppc_set_reg_val() rejects the write with -EOPNOTSUPP
>>> because the entry is not an ACPI_TYPE_BUFFER.
>>>
>>> shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init()
>>> fails, cpufreq_register_driver() ends up with an empty policy list and
>>> returns -ENODEV, and amd-pstate refuses to load at all:
>>>
>>>   amd_pstate: failed to set auto_sel, ret: -95
>>>   amd_pstate: Failed to initialize CPU 0: -95
>>>   ...
>>>   amd_pstate: failed to register with return -19
>>>
>>> Skip the write when the register already holds the value the requested mode
>>> needs.  Active and guided mode are fixed on these platforms, which report
>>> auto_sel as 1, while passive mode still fails to load on a platform that
>>> cannot disable autonomous selection, exactly as it did before the
>>> offending commit.
>>>
>>> Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems")
>>> Cc: stable@vger.kernel.org
>>> Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
>>> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
>>> Tested-by: LFRon <ronforever@outlook.com>
>>> Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
>>> ---
>>> changelog v3:
>>> Include the K Prateek Nayak reviews to remove that ternary op base on current
>>> condition now have.
>>>
>>> v2 link:
>>> https://lore.kernel.org/stable/c3eb86bd-70a6-4bb2-8eff-b2a3c0817514@amd.com/#R
>>> changelog v2:
>>> Accecpt and tested the K Prateek Nayak reviews.
>>> v1 link:
>>> https://lore.kernel.org/stable/20260918054808.48999-1-guanwentao@uniontech.com/#R
>>> ---
>>> ---
>>> drivers/cpufreq/amd-pstate.c | 6 ++++--
>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
>>> index 80d99ba1902c9..2d1f5292d1738 100644
>>> --- a/drivers/cpufreq/amd-pstate.c
>>> +++ b/drivers/cpufreq/amd-pstate.c
>>> @@ -532,8 +532,10 @@ static int shmem_init_perf(struct amd_cpudata *cpudata)
>>>  		return 0;
>>>  	}
>>>
>>> -	ret = cppc_set_auto_sel(cpudata->cpu,
>>> -			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
>>> +	if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel)
>>> +		return 0;
>>> +
>>> +	ret = cppc_set_auto_sel(cpudata->cpu, !auto_sel);
>>>
>>>  	if (ret)
>>>  		pr_warn("failed to set auto_sel, ret: %d\n", ret);
>>> --
>>> 2.30.2
>> 
>> Ping? Nearly a month passed, anything update?
>
>On a similar issue here
>https://lore.kernel.org/all/851316da-2cfa-4a22-947c-1838532d05cf@amd.com/
>Mario had recently pointed out that this might be a BIOS issue on
>systems that may have MSR interface but running an old BIOS that does
>not advertise the CPUID bit.
Seem same issue.

>
>Could you please share your system details here and check if you are
>running the latest BIOS from your vendor?

Emmm, the user report that dmesg showed running on this laptop:
DMI: METAPHYUNI MetamechBook01/MetamechBook01, BIOS AHP958_V00.01_T015A5ME1 02/22/2024
which vendor not ship new BIOS,
but it is verified in AMD Advantage: https://www.amd.com/en/gaming/laptops/advantage-premium.html ...

He also helped me to test the kernel patch.

BRs
Wentao Guan