[mt76][mt7921] Question about host-visible deterministic TX scheduling / TX completion timestamps

[Zitong Zhao]

Hi mt76 maintainers,

Resending as plain text because the previous HTML mail was rejected by
linux-mediatek.

We are working on a deterministic Wi-Fi TDMA research prototype using
MT7921/MT7922 with the mt76/mt7921e driver.

We would like to understand whether the MT7921/MT7922
hardware/firmware exposes any supported host-visible primitive for:

1. TSF-scheduled TX or hardware-timed queue release
2. firmware TX queue admission / queue pause-resume
3. reliable per-packet firmware/PHY TX completion timestamps
4. TWT service-period control usable for deterministic UL/DL scheduling

>From the public mt76 driver and our local diagnostics, we currently observe:

- RX MACTIME is available and useful for RX-side timestamping.
- TXS can be forced for diagnostics, but coverage is partial/asymmetric.
- WTBL_QUERY returns only a short status-like response in our setup.
- TWT_AGRT_UPDATE returns ACK/status, but we have not found evidence
that it provides host-controllable deterministic queue admission.
- We did not find an exposed TSF-scheduled TX path in mt7921e.

Could you confirm whether this hardware/firmware stack supports any
host-visible deterministic TX scheduling or reliable per-packet TX
completion timestamp interface?

If this is not available in the public mt76 driver, is it a firmware
limitation, or is there a documented MediaTek interface available
through another channel?

Hardware/firmware in our setup:
- AP side: MT7961/MT7921e path
- STA side: MT7922/RZ616-family, mt7921e path
- Driver base: mt76/mt7921e with local research diagnostics

We do not need confidential details on the public mailing list. A
yes/no answer about whether such primitives exist would already be
very helpful. If this requires MediaTek confidential documentation or
an NDA channel, could you point us to the right contact/process?

Thanks,
Zitong Zhao
Cyber Physical System Lab from Shanghai Jiao Tong University