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author | Alex Deucher <alexander.deucher@amd.com> | 2023-12-13 23:22:29 +0300 |
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committer | Alex Deucher <alexander.deucher@amd.com> | 2023-12-13 23:22:29 +0300 |
commit | 4f914d75a1238555764ba4c2ae1116ed062bd976 (patch) | |
tree | de0dcf122d904e5783689d1bb56b9b3ca5110fa2 /Documentation | |
parent | 0188006d7c797a37c04471a2b4a34a7dfb21f363 (diff) | |
parent | 58e82a62669da52e688f4a8b89922c1839bf1001 (diff) | |
download | linux-4f914d75a1238555764ba4c2ae1116ed062bd976.tar.xz |
Merge tag 'platform-drivers-x86-amd-wbrf-v6.8-1' into amd-drm-next
Immutable branch between pdx86 amd wbrf branch and wifi / amdgpu due for the v6.8 merge window
platform-drivers-x86-amd-wbrf-v6.8-1: v6.7-rc1 + AMD WBRF support
for merging into the wifi subsys and amdgpu driver for 6.8.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/driver-api/index.rst | 1 | ||||
-rw-r--r-- | Documentation/driver-api/wbrf.rst | 78 |
2 files changed, 79 insertions, 0 deletions
diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index f549a68951d7..8bc4ebe7a36f 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -115,6 +115,7 @@ available subsections can be seen below. hte/index wmi dpll + wbrf .. only:: subproject and html diff --git a/Documentation/driver-api/wbrf.rst b/Documentation/driver-api/wbrf.rst new file mode 100644 index 000000000000..f48bfa029813 --- /dev/null +++ b/Documentation/driver-api/wbrf.rst @@ -0,0 +1,78 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +================================= +WBRF - Wifi Band RFI Mitigations +================================= + +Due to electrical and mechanical constraints in certain platform designs +there may be likely interference of relatively high-powered harmonics of +the GPU memory clocks with local radio module frequency bands used by +certain Wifi bands. + +To mitigate possible RFI interference producers can advertise the +frequencies in use and consumers can use this information to avoid using +these frequencies for sensitive features. + +When a platform is known to have this issue with any contained devices, +the platform designer will advertise the availability of this feature via +ACPI devices with a device specific method (_DSM). +* Producers with this _DSM will be able to advertise the frequencies in use. +* Consumers with this _DSM will be able to register for notifications of +frequencies in use. + +Some general terms +================== + +Producer: such component who can produce high-powered radio frequency +Consumer: such component who can adjust its in-use frequency in +response to the radio frequencies of other components to mitigate the +possible RFI. + +To make the mechanism function, those producers should notify active use +of their particular frequencies so that other consumers can make relative +internal adjustments as necessary to avoid this resonance. + +ACPI interface +============== + +Although initially used by for wifi + dGPU use cases, the ACPI interface +can be scaled to any type of device that a platform designer discovers +can cause interference. + +The GUID used for the _DSM is 7B7656CF-DC3D-4C1C-83E9-66E721DE3070. + +3 functions are available in this _DSM: + +* 0: discover # of functions available +* 1: record RF bands in use +* 2: retrieve RF bands in use + +Driver programming interface +============================ + +.. kernel-doc:: drivers/platform/x86/amd/wbrf.c + +Sample Usage +============= + +The expected flow for the producers: +1. During probe, call `acpi_amd_wbrf_supported_producer` to check if WBRF +can be enabled for the device. +2. On using some frequency band, call `acpi_amd_wbrf_add_remove` with 'add' +param to get other consumers properly notified. +3. Or on stopping using some frequency band, call +`acpi_amd_wbrf_add_remove` with 'remove' param to get other consumers notified. + +The expected flow for the consumers: +1. During probe, call `acpi_amd_wbrf_supported_consumer` to check if WBRF +can be enabled for the device. +2. Call `amd_wbrf_register_notifier` to register for notification +of frequency band change(add or remove) from other producers. +3. Call the `amd_wbrf_retrieve_freq_band` initally to retrieve +current active frequency bands considering some producers may broadcast +such information before the consumer is up. +4. On receiving a notification for frequency band change, run +`amd_wbrf_retrieve_freq_band` again to retrieve the latest +active frequency bands. +5. During driver cleanup, call `amd_wbrf_unregister_notifier` to +unregister the notifier. |