RE: [PATCH 1/2] wifi: rtw89: phy: increase RF calibration timeouts for USB transport

Ping-Ke Shih
2026-04-14T06:32:39Z

Louis Kotze <loukot@gmail.com> wrote:
> USB transport adds significant latency to H2C/C2H round-trips used
> by RF calibration. The existing timeout values were designed for PCIe
> and are too tight for USB, causing "failed to wait RF DACK",
> "failed to wait RF TSSI" and similar errors on USB adapters.
>
> Apply a 4x timeout multiplier when the device uses USB transport.
> The multiplier is applied in rtw89_phy_rfk_report_wait() so all
> calibrations benefit without changing any call sites or PCIe
> timeout values.
>
> The 4x multiplier was chosen based on measured data from two
> independent testers (RTL8922AU, 6GHz MLO and 2.4/5GHz):
>
> Calibration PCIe timeout Max measured (USB) 4x timeout
> PRE_NTFY 5ms 1ms 20ms
> DACK 58ms 72ms 232ms
> RX_DCK 128ms 374ms 512ms
> TSSI normal 20ms 24ms 80ms
> TSSI scan 6ms 14ms 24ms
> TXGAPK 54ms 18ms 216ms
> IQK 84ms 53ms 336ms
> DPK 34ms 30ms 136ms
>
> Tested with RTL8922AU on 6GHz MLO (5GHz + 6GHz simultaneous):
> 25 connect/disconnect cycles with zero failures.
>
> Signed-off-by: Louis Kotze <loukot@gmail.com>

Looks good to me. But please change comment style.

> ---
> drivers/net/wireless/realtek/rtw89/phy.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/net/wireless/realtek/rtw89/phy.c b/drivers/net/wireless/realtek/rtw89/phy.c
> index e70d0e283..4d809df8b 100644
> --- a/drivers/net/wireless/realtek/rtw89/phy.c
> +++ b/drivers/net/wireless/realtek/rtw89/phy.c
> @@ -3956,6 +3956,13 @@ int rtw89_phy_rfk_report_wait(struct rtw89_dev *rtwdev, const char *rfk_name,
> struct rtw89_rfk_wait_info *wait = &rtwdev->rfk_wait;
> unsigned long time_left;
>
> + /* USB transport adds latency to H2C/C2H round-trips, so RF
> + * calibrations take longer than on PCIe. Apply a 4x multiplier
> + * to avoid spurious timeouts.
> + */

For now, we don't apply networking specific comment style. Keep first line '/*'.

> + if (rtwdev->hci.type == RTW89_HCI_TYPE_USB)
> + ms *= 4;
> +
> /* Since we can't receive C2H event during SER, use a fixed delay. */
> if (test_bit(RTW89_FLAG_SER_HANDLING, rtwdev->flags)) {
> fsleep(1000 * ms / 2);
> --
> 2.53.0