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

[Rafael J. Wysocki (Intel)]

Hi Sumit,

On Fri, Oct 30, 2026 at 6:28 PM Sumit Gupta <sumitg@xxxxxxxxxx> 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@xxxxxxxxxx/
>
> 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@xxxxxxxxxx/
> v6: https://lore.kernel.org/lkml/20260717215330.2215058-1-sumitg@xxxxxxxxxx/
> v5: https://lore.kernel.org/lkml/20260615185934.2383514-1-sumitg@xxxxxxxxxx/
> v4: https://lore.kernel.org/lkml/20260527194626.185286-1-sumitg@xxxxxxxxxx/
> v3: https://lore.kernel.org/lkml/20260514194822.1841748-1-sumitg@xxxxxxxxxx/
> v2: https://lore.kernel.org/lkml/20260430142430.755437-1-sumitg@xxxxxxxxxx/
> v1: https://lore.kernel.org/lkml/20260427051823.280419-1-sumitg@xxxxxxxxxx/
>
> --

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!