Re: [PATCH V4 1/8] drivers/acpi: Add support for Wifi band RF mitigations

Limonciello, Mario
2023-06-23T15:57:50Z

On 6/23/2023 9:52 AM, Rafael J. Wysocki wrote:
> On Wed, Jun 21, 2023 at 7:47 AM Evan Quan <evan.quan@amd.com> wrote:
>> From: Mario Limonciello <mario.limonciello@amd.com>
>>
>> Due to electrical and mechanical constraints in certain platform designs
>> there may be likely interference of relatively high-powered harmonics of
>> the (G-)DDR memory clocks with local radio module frequency bands used
>> by Wifi 6/6e/7.
>>
>> To mitigate this, AMD has introduced an ACPI based mechanism that
>> devices can use to notify active use of particular frequencies so
>> that devices can make relative internal adjustments as necessary
>> to avoid this resonance.
>>
>> In order for a device to support this, the expected flow for device
>> driver or subsystems:
>>
>> Drivers/subsystems contributing frequencies:
>>
>> 1) During probe, check `wbrf_supported_producer` to see if WBRF supported
> The prefix should be acpi_wbrf_ or acpi_amd_wbrf_ even, so it is clear
> that this uses ACPI and is AMD-specific.

I guess if we end up with an intermediary library approach
wbrf_supported_producer makes sense and that could call acpi_wbrf_*.

But with no intermediate library your suggestion makes sense.

I would prefer not to make it acpi_amd as there is no reason that
this exact same problem couldn't happen on an
Wifi 6e + Intel SOC + AMD dGPU design too and OEMs could use the
same mitigation mechanism as Wifi6e + AMD SOC + AMD dGPU too.

>
> Whether or not there needs to be an intermediate library wrapped
> around this is a different matter.