It was noticed that Mediatek's MT7915 does not only require calibration of
the normal rates (configured via DT) but also some backoff values for
beamforming. The proprietary driver loads this from some file in the
firmware folder. But for the the upstream driver, it is necessary to get
them from the same place as the normal limits - in this case from the
devicetree.
They released the support for this [1,2] in their own SDK but
without any kind of documentation. And it was (to my knowledge) never
forwarded to upstream. But since also (in my case) OpenWrt needs correct
calibration for this WiFi chip, we should get this upstreamed.
I try to my best to provide some sensible information about the patch and
the DT entries. If anyone else has more information about it (to improve
the descriptions), please feel free to comment and provide some
enhanced/corrected version.
The patch from Shayne Chen was only rebased and modified to perform byte
reads from the DT [3]. Besides this, only a commit message was added,
MTK_DEBUG parts were dropped and some checkpatch problems were fixed.
Regards,
Sven
[1] https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/f0d2527deb4f91592b6486a5c98ea3f584f76a61
[2] https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/737340322ab22b138fd200e020d61ffdbe3e36a9/autobuild/autobuild_5.4_mac80211_release/package/kernel/mt76/patches/1022-wifi-mt76-mt7915-add-bf-backoff-limit-table-support.patch
[3] https://lore.kernel.org/r/20250917-fix-power-limits-v1-1-616e859a9881@simonwunderlich.de
Signed-off-by: Sven Eckelmann (Plasma Cloud) <se@simonwunderlich.de>
---
Changes in v2:
- add [PATCH mt76] as requested by Zhi-Jun You
- Link to v1: https://lore.kernel.org/r/20250924-backoff-table-support-v1-0-20e50fbc59de@simonwunderlich.de
---
Shayne Chen (1):
wifi: mt76: mt7915: add bf backoff limit table support
Sven Eckelmann (Plasma Cloud) (2):
dt-bindings: net: wireless: mt76: Document power-limits country property
dt-bindings: net: wireless: mt76: introduce backoff limit properties
.../bindings/net/wireless/mediatek,mt76.yaml | 65 ++++++++
drivers/net/wireless/mediatek/mt76/debugfs.c | 4 +-
drivers/net/wireless/mediatek/mt76/eeprom.c | 38 ++++-
drivers/net/wireless/mediatek/mt76/mt76.h | 8 +
.../net/wireless/mediatek/mt76/mt7915/debugfs.c | 74 ++++++++-
drivers/net/wireless/mediatek/mt76/mt7915/init.c | 7 +
drivers/net/wireless/mediatek/mt76/mt7915/main.c | 2 +-
drivers/net/wireless/mediatek/mt76/mt7915/mcu.c | 182 ++++++++++++++++-----
drivers/net/wireless/mediatek/mt76/mt7915/mcu.h | 6 +
drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h | 9 +-
.../net/wireless/mediatek/mt76/mt7915/testmode.c | 2 +-
11 files changed, 342 insertions(+), 55 deletions(-)
---
base-commit: b36d55610215a976267197ddc914902c494705d7
change-id: 20250917-backoff-table-support-99218823576d
prerequisite-change-id: 20250917-fix-power-limits-5ce07b993681:v1
prerequisite-patch-id: 964626eea847052cefc907ef0f01286a080fdc3c
Best regards,
--
Sven Eckelmann (Plasma Cloud) <se@simonwunderlich.de>