RTL8822CU, RTL8822BU, and RTL8821CU don't need BIT_EN_PRE_CALC.
In fact, RTL8822BU in USB 3 mode doesn't pass all the frames to the
driver, resulting in much lower download speed than normal:
$ iperf3 -c 192.168.0.1 -R
Connecting to host 192.168.0.1, port 5201
Reverse mode, remote host 192.168.0.1 is sending
[ 5] local 192.168.0.50 port 43062 connected to 192.168.0.1 port 5201
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.00 sec 26.9 MBytes 225 Mbits/sec
[ 5] 1.00-2.00 sec 7.50 MBytes 62.9 Mbits/sec
[ 5] 2.00-3.00 sec 8.50 MBytes 71.3 Mbits/sec
[ 5] 3.00-4.00 sec 8.38 MBytes 70.3 Mbits/sec
[ 5] 4.00-5.00 sec 7.75 MBytes 65.0 Mbits/sec
[ 5] 5.00-6.00 sec 8.00 MBytes 67.1 Mbits/sec
[ 5] 6.00-7.00 sec 8.00 MBytes 67.1 Mbits/sec
[ 5] 7.00-8.00 sec 7.75 MBytes 65.0 Mbits/sec
[ 5] 8.00-9.00 sec 7.88 MBytes 66.1 Mbits/sec
[ 5] 9.00-10.00 sec 7.88 MBytes 66.1 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.02 sec 102 MBytes 85.1 Mbits/sec 224 sender
[ 5] 0.00-10.00 sec 98.6 MBytes 82.7 Mbits/sec receiver
Don't set BIT_EN_PRE_CALC. Then the speed is much better:
% iperf3 -c 192.168.0.1 -R
Connecting to host 192.168.0.1, port 5201
Reverse mode, remote host 192.168.0.1 is sending
[ 5] local 192.168.0.50 port 39000 connected to 192.168.0.1 port 5201
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.00 sec 52.8 MBytes 442 Mbits/sec
[ 5] 1.00-2.00 sec 71.9 MBytes 603 Mbits/sec
[ 5] 2.00-3.00 sec 74.8 MBytes 627 Mbits/sec
[ 5] 3.00-4.00 sec 75.9 MBytes 636 Mbits/sec
[ 5] 4.00-5.00 sec 76.0 MBytes 638 Mbits/sec
[ 5] 5.00-6.00 sec 74.1 MBytes 622 Mbits/sec
[ 5] 6.00-7.00 sec 74.0 MBytes 621 Mbits/sec
[ 5] 7.00-8.00 sec 76.0 MBytes 638 Mbits/sec
[ 5] 8.00-9.00 sec 74.4 MBytes 624 Mbits/sec
[ 5] 9.00-10.00 sec 63.9 MBytes 536 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 717 MBytes 601 Mbits/sec 24 sender
[ 5] 0.00-10.00 sec 714 MBytes 599 Mbits/sec receiver
Fixes: 002a5db9a52a ("wifi: rtw88: Enable USB RX aggregation for 8822c/8822b/8821c")
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@xxxxxxxxx>
---
The code in the official drivers is a little broken. It sets
BIT_EN_PRE_CALC and then immediately unsets it. I didn't notice that
before.
Maybe this should go to kernel 6.12, if it's not too late. Commit 002a5db9a52a
("wifi: rtw88: Enable USB RX aggregation for 8822c/8822b/8821c") first appears
in 6.12.
---
drivers/net/wireless/realtek/rtw88/usb.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
index 10b840d59ebd..74ee5bdbb036 100644
--- a/drivers/net/wireless/realtek/rtw88/usb.c
+++ b/drivers/net/wireless/realtek/rtw88/usb.c
@@ -772,7 +772,6 @@ static void rtw_usb_dynamic_rx_agg_v1(struct rtw_dev *rtwdev, bool enable)
u8 size, timeout;
u16 val16;
- rtw_write32_set(rtwdev, REG_RXDMA_AGG_PG_TH, BIT_EN_PRE_CALC);
rtw_write8_set(rtwdev, REG_TXDMA_PQ_MAP, BIT_RXDMA_AGG_EN);
rtw_write8_clr(rtwdev, REG_RXDMA_AGG_PG_TH + 3, BIT(7));
--
2.46.0
