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

Louis Kotze
2026-04-10T08:00:36Z

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>
---
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.
+ */
+ 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