Hi Jes,
Hi all,
Chris (writing code, testing) and me (testing) are working [1] on
re-newing the Wi-Fi Alliance certification of an IoT gateway (STA) which
uses the Realtek RTL8188CUS chip, and is (now) running Linux 5.10+ with
the rtl8xxxu driver, firmware version 88.2 [2]. The existing
certification [3] has been done using the RealTek-provided 8192cu driver
[4] and and Linux 3.19.
While the rtl8xxxu in upstream is *very* stable, it lacks some features
which are needed for the certification. I tried to summarize this in the
wiki [1].
The following has been implemented by Chris (on top of mainline):
- STBC Receive
- TX power configuration (using the iw command, not regdb)
Still missing:
- WMM support
- A-MSDU RX support
- TX power by rate
WIP (See also Chris' mail from earlier today):
- A-MPDU
- Rate adaption
- TX descriptors
The motivation for writing this mail is that we we are currently blocked
by an issue which we can not resolve already for some months: The
re-transmission percentage of the rtl8xxxu is too high (rtl8192cu is the
same) - way higher than what 8192cu achieves. According to Wireshark,
the retransmission rate is always between 15-65% for the rtl8xxxu, while
the realtek-provided 8192cu stays below 5%, often averaging at less than
1% in my setup.
Examples with an Linksys WRT3200ACM AP (RA/TA: 24:f5:a2:c0:4e:b1, DA/SA:
00:60:6e:00:07:7d, SSID customer-testwifi) and the DUT
(00:1d:43:c0:19:8a) running iperf3 (TCP, TX):
rtl8xxxu:
- 65% retries, many addresses reported which do not actually exists
- Code: [5]
- Captures: [7]
891cu:
- 0.9% retries, no ghost addresses captured
- Code: [6]
- Captures: [8]
I'd be really grateful for any kind of ideas, pointers, help.
Kind regards,
Reto
[1] Wiki entry (slightly outdated):
https://wireless.wiki.kernel.org/en/users/wi-fi-alliance-certification
[2] rtl8912cu firmware v88.2, part of linux-firmware 20201118:
https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/commit/rtlwifi/rtl8192cufw_TMSC.bin?id=2ea86675db1349235e9af0a9d0372b72da4db259
[3] Existing certification:
https://api.cert.wi-fi.org/api/certificate/download/public?variantId=14856
[4] https://github.com/husqvarnagroup/smart-garden-gateway-seluxit-8192cu
[5] Most recent rtl8xxxu development:
https://github.com/husqvarnagroup/linux/commit/909f13c8fd45260a622d148882030624d492c54f
[6] 8192cu for Linux 5.10+:
https://github.com/husqvarnagroup/realtek-8192cu_rtl8188cus
[7] pcap:
https://files.reto-schneider.ch/diesunddas/rtl8xxxu/2021-05-10/rtl8xxxu-65%25-retries.pcapng.gz
shell:
https://files.reto-schneider.ch/diesunddas/rtl8xxxu/2021-05-10/rtl8xxxu-65%25-retries-shell.log
[8] pcap:
https://files.reto-schneider.ch/diesunddas/rtl8xxxu/2021-05-10/8192cu-0.9%25-retries.pcapng.gz
shell:
https://files.reto-schneider.ch/diesunddas/rtl8xxxu/2021-05-10/8192cu-0.9%25-retries-shell.log
