Re: [PATCH rtw-next v10 3/3] wifi: rtw88: time the countdown downloads from the TBTT

[Luka Gejak]

Hi Mehmet,

Thanks for the v10. Two comments below.

On November 11, 2026 1:15:25 PM GMT+01:00, Mehmet Fide
<mehmet.fide@xxxxxxxxx> wrote:

> diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
> index 2d81aaeed0d7..c30aa938f9a9 100644
> --- a/drivers/net/wireless/realtek/rtw88/fw.c
> +++ b/drivers/net/wireless/realtek/rtw88/fw.c

[ ... ]

> +static void rtw_fw_csa_queue(struct rtw_dev *rtwdev, struct ieee80211_vif *vif,
> +                          bool start)
>  {
>       u32 interval = ieee80211_tu_to_usec(vif->bss_conf.beacon_int);
> +     u64 tsf = rtw_fw_read_tsf(rtwdev);

As far as I can see rtw88 never writes the beacon interval register
(0x554), while rtlwifi writes it on BSS_CHANGED_BEACON_INT. So the
hardware probably keeps its default, and the TBTTs computed here from
bss_conf.beacon_int would only match the air at 100 TU.

Could you check the beacon spacing in a capture with beacon_int=200? If
it stays at 100 TU, that is a separate bug. Would you be willing to send
a fix for that too?

[ ... ]

> +     delay = rtwdev->csa_tbtt + RTW_CSA_TBTT_MARGIN_US - tsf;
> +     if (delay > interval + RTW_CSA_TBTT_MARGIN_US ||
> +         delay < -(s64)interval) {
> +             /* the TSF jumped: restart from the next TBTT */
> +             div_u64_rem(tsf, interval, &rem);
> +             rtwdev->csa_tbtt = tsf - rem + interval;
> +             delay = rtwdev->csa_tbtt + RTW_CSA_TBTT_MARGIN_US - tsf;
> +     }

rtw88 sets BIT_DIS_TSF_UDT for AP and IBSS and has no reset_tsf op, so I
think this mostly catches a download that ran more than a beacon
interval late, not a TSF jump. Maybe say that in the comment?

The start case computes the same next TBTT, so it could share this
branch:

        rtwdev->csa_tbtt += interval;
        delay = rtwdev->csa_tbtt + RTW_CSA_TBTT_MARGIN_US - tsf;
        if (start || delay > interval + RTW_CSA_TBTT_MARGIN_US ||
            delay < -(s64)interval) {

Best regards,
Luka Gejak