On 26/03/2025 03:44, Ping-Ke Shih wrote: > Bitterblue Smith <rtl8821cerfe2@xxxxxxxxx> wrote: >> Hi, >> >> I ran into a problem with the RTL8812BU. If I load it a bit in USB 3 >> mode, like with "iperf3 -c 192.168.0.1 -R -t 60" the connection often >> stops working. It may take a few tries. It still receives beacons but >> the AP can't be pinged anymore. >> >> Looking at the registers with >> "watch cat /sys/kernel/debug/ieee80211/phy*/rtw88/mac_2", I noticed >> the high half of register 0x240 was steadily increasing. >> >> Register 0x240 is called REG_FIFOPAGE_INFO_5. The driver writes the >> number of pages allocated to the public queue into the low half. >> The high half indicates the number of pages currently available. >> The number of available pages was steadily increasing, beyond the >> total number of pages: >> >> 00000240 072b070b 0003fa00 0003fe00 0003fa60 >> 00000240 0737070b 0003fa00 0003fe00 0003fa60 >> 00000240 073b070b 0003fa00 0003fe00 0003fa60 >> 00000240 0741070b 0003fa00 0003fe00 0003fa60 >> 00000240 0741070b 0003fa00 0003fe00 0003fa60 >> 00000240 074f070b 0003fa00 0003fe00 0003fa60 >> 00000240 075d070b 0003fa00 0003fe00 0003fa60 >> >> Normal values when the device is functional (and idle): >> >> 00000240 070b070b 0003fa00 0003fe00 0003fa60 >> >> When register 0x240 has strange values, register 0x210 >> (REG_TXDMA_STATUS) has the value 5. Normally register 0x210 is 0. >> >> All this only happens in USB 3 mode. Everything is fine in USB 2 mode. > > I checked with internal USB team. The USB 3 mode can only work on 5GHz, > because electrical interference between USB 3 clock and WiFi 2.4 GHz > band. Could you check if it works on 5GHz? > Thank you for taking this to them. It doesn't work on 5 GHz. I was already using my 5 GHz network on channel 100. >> >> I tried to disable USB RX and TX aggregation, SUPPORTS_AMSDU_IN_AMPDU, >> and TX_AMSDU. None of that helped. >> >> This problem happens also with this driver: >> https://github.com/morrownr/88x2bu-20210702 >> and with v5.13.1.1-1-g6f2541ef2.20240507_COEX20220812-18317b7b. > > By default, it only supports USB 2 mode. Have you changed the driver? > I did not change the driver. I set the module parameter rtw_switch_usb_mode to 1. It makes the driver switch to USB 3 mode. I forgot to say that I also tested Windows 10 with the driver from TP-Link (I think). I tried alternating upload tests and download tests over and over, I left iperf3 running for many minutes. It was very difficult to make it fail. I think only one time iperf3 reported 0 speed for a few seconds but it recovered by itself. I don't know how to examine the hardware registers (0x210, 0x240) in Windows, so I can't say for sure that the problem doesn't happen there. But it looks much better than in Linux. It was definitely in USB 3 mode, the speeds were 500-600 Mbps. >> I see >> the same strange values in register 0x240 in >> /proc/net/rtl88x2bu/wlp3s0f3u4/mac_reg_dump. >> >> My test device is TP-Link Archer T3U Plus, with USB ID 2357:0138. >> My system is Lenovo Ideapad 3 15ADA6 with AMD Athlon Gold 3150U CPU. >> >> Can this be fixed somehow? I saw the other drivers have some code in >> rtw_sreset.c to power off and on the device when register 0x210 is >> non-zero, but that seems suboptimal.
