Re: [PATCH v8 0/3] ACPI / cpufreq: CPPC: Add ospm_nominal_perf support

[Sumit Gupta <sumitg@nvidia.com>]

Hi Rafael,


On 06/11/26 22:31, Rafael J. Wysocki (Intel) wrote:
> External email: Use caution opening links or attachments
> 
> 
> On Fri, Nov 6, 2026 at 5:59 PM Christian Loehle
> <christian.loehle@arm.com> wrote:
>>
>> On 11/6/26 16:08, Rafael J. Wysocki (Intel) wrote:
>>> Hi Sumit,
>>>
>>> On Fri, Oct 30, 2026 at 6:28 PM Sumit Gupta <sumitg@nvidia.com> wrote:
>>>>
>>>> This series adds support for the OSPM Nominal Performance register
>>>> (ACPI 6.6, Section 8.4.6.1.2.6) to the CPPC ACPI and cpufreq drivers.
>>>>
>>>> Unlike the read-only Nominal Performance register, OSPM Nominal
>>>> Performance is writable and lets OSPM request a nominal level below
>>>> the platform-reported nominal. The platform treats performance above
>>>> this level as boost and below as throttle.
>>>>
>>>>   - Patch 1: adds ACPI helpers to write the register and to check that
>>>>     the platform supports it.
>>>>
>>>>   - Patch 2: adds the per-policy ospm_nominal_freq attribute in kHz. The
>>>>     value is kept across CPU hotplug and suspend/resume. The register
>>>>     cannot be read back, so a read returns the last value written.
>>>>
>>>>   - Patch 3: uses the OSPM nominal as the maximum frequency while boost
>>>>     is off. Lowering the nominal creates a boost range on a platform
>>>>     that has none, and boost can then be enabled.
>>>>
>>>> This series applies on top of v7 of:
>>>>    cpufreq: CPPC: Preserve OSPM-set registers across hotplug and unload
>>>>    https://lore.kernel.org/lkml/20261030092416.1993889-1-sumitg@nvidia.com/
>>>>
>>>> v7 -> v8:
>>>>   - Rebase on Christian's CPPC fixes series.
>>>>   - Patch 1:
>>>>     - use cpc_is_writable() from that series and drop cpc_reg_writable().
>>>>     - add the register to the list of controls the driver writes.
>>>>     - take cpc_desc_lock in cppc_ospm_nominal_perf_supported(), so the
>>>>       descriptor cannot be removed during the check.
>>>>   - Patch 2:
>>>>     - make ospm_nominal_freq read-write. A read returns the last value
>>>>       written, or "<unset>" before the first write. (Christian, Mario)
>>>>     - keep saving the values in the store handler, not at init(), so
>>>>       the driver writes the register only after the OS sets it. (Pierre)
>>>>   - Patch 3:
>>>>     - document in the ABI file how the OSPM nominal sets cpuinfo_max_freq
>>>>       and caps scaling_max_freq.
>>>>
>>>> Sumit Gupta (3):
>>>>    ACPI: CPPC: Add ospm_nominal_perf support
>>>>    cpufreq: CPPC: Add ospm_nominal_freq attribute
>>>>    cpufreq: CPPC: Reflect the OSPM nominal in boost and limits
>>>>
>>>>   .../ABI/testing/sysfs-devices-system-cpu      |  31 ++++
>>>>   drivers/acpi/cppc_acpi.c                      |  44 +++++
>>>>   drivers/cpufreq/cppc_cpufreq.c                | 173 +++++++++++++++++-
>>>>   include/acpi/cppc_acpi.h                      |  10 +
>>>>   4 files changed, 248 insertions(+), 10 deletions(-)
>>>>
>>>> v7: https://lore.kernel.org/lkml/20260807214837.863209-1-sumitg@nvidia.com/
>>>> v6: https://lore.kernel.org/lkml/20260717215330.2215058-1-sumitg@nvidia.com/
>>>> v5: https://lore.kernel.org/lkml/20260615185934.2383514-1-sumitg@nvidia.com/
>>>> v4: https://lore.kernel.org/lkml/20260527194626.185286-1-sumitg@nvidia.com/
>>>> v3: https://lore.kernel.org/lkml/20260514194822.1841748-1-sumitg@nvidia.com/
>>>> v2: https://lore.kernel.org/lkml/20260430142430.755437-1-sumitg@nvidia.com/
>>>> v1: https://lore.kernel.org/lkml/20260427051823.280419-1-sumitg@nvidia.com/
>>>>
>>>> --
>>>
>>> This would be good to go except that it doesn't apply for me on top of 7.4-rc1.
>>>
>>> Can you please rebase it and resend, with Christian's tags included?
>>>
>>> Thanks!
>>
>> It's based on the hotplug/resume series, I guess Sumit could post them as a combined patchset
> 
> That would help.

Sure, posted a combined series on top of 7.4-rc1, with Christian's
tags [1].

[1] https://lore.kernel.org/lkml/20261106193304.3347374-1-sumitg@nvidia.com/

Thanks,
Sumit