RE: rtw88: RTL8812BU TX FIFO corruption (?) in USB 3 mode

[Ping-Ke Shih <pkshih@realtek.com>]

Bitterblue Smith <rtl8821cerfe2@gmail.com> 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?

> 
> 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 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.