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

[Zitong Zhao]

Hi,

Just following up on this MT7921/MT7922 question.

A yes/no answer on whether this hardware/firmware stack exposes any
supported host-visible primitive for TSF-scheduled TX, firmware queue
admission, or reliable per-packet firmware/PHY TX completion
timestamps would already be very helpful.

If this is not available through the public mt76 driver, could you
point us to the right MediaTek documentation / NDA / direct-customer
channel?

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

On Mon, Jun 8, 2026 at 1:28 PM Zitong Zhao <zitongzhaooo at gmail.com> wrote:
>
> 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