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Date: Thu, 21 Mar 2024 11:55:47 +0100
From: Konstantin Kletschke <konstantin.kletschke@inside-m2m.de>
To: linux-wireless@vger.kernel.org
Subject: AP mode on RTW88 8821cs
Message-ID: <ZfwSM0paZg23iEPS@hephaistos.inside-m2m.de>
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We have a rockchip rk3328 board with an 8821cs chip connected via SDIO.
Well, cs impiles SDIO, cu is USB variant.

Normally thinks work quite well for use but we do not get AP mode to
work.
We use 6.5.13 kernel with our customized DT and the in kernel 8821cs
driver:

rtw88_8821cs           12288  0
onboard_usb_hub        12288  0
rtw88_8821c            81920  1 rtw88_8821cs
crct10dif_ce           12288  1
rtw88_sdio             24576  1 rtw88_8821cs
rtw88_core            167936  2 rtw88_8821c,rtw88_sdio
mac80211              929792  2 rtw88_sdio,rtw88_core
libarc4                12288  1 mac80211
cfg80211              921600  2 rtw88_core,mac80211

We tried with wpa_cli and hostapd but to no avail.
I tried hostapd with wlan0 and eth0 bridged into br0, the SSID appears
in the wlan search results in other devices, connectig _seems_ to work
but getting an IP is not possible.

What my colleauge and me especially noticed, the TX counter for the
wlan0 interface in this use case runs, RX stays at 0:

br0       Link encap:Ethernet  HWaddr 4A:86:7D:63:5C:59
          inet addr:10.16.10.103  Bcast:10.16.255.255  Mask:255.255.0.0
          inet6 addr: fe80::4886:7dff:fe63:5c59/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:111361 errors:0 dropped:3479 overruns:0 frame:0
          TX packets:28144 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:13333769 (12.7 MiB)  TX bytes:3847859 (3.6 MiB)

eth0      Link encap:Ethernet  HWaddr 86:E0:C0:EA:FA:A8
          inet6 addr: fe80::84e0:c0ff:feea:faa8/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:112803 errors:0 dropped:219 overruns:0 frame:0
          TX packets:28405 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:15102222 (14.4 MiB)  TX bytes:3891727 (3.7 MiB)
          Interrupt:51

wlan0     Link encap:Ethernet  HWaddr F0:B0:40:4F:70:BC
          inet6 addr: fe80::f2b0:40ff:fe4f:70bc/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:123446 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:18783966 (17.9 MiB)

In order to provide useful debug information, what should I look into?

Is it a known issue or should AP mode work flawlessly with those
drivers, which implies I forgot something.
When I use my software with an external USB WLAN stick with another
driver, exchange all wlan0 by wlan1 occurences only:

rtl8xxxu              192512  0
rtl8192cu              81920  0
rtl_usb                16384  1 rtl8192cu
rtl8192c_common        65536  1 rtl8192cu
rtlwifi               118784  3 rtl8192c_common,rtl_usb,rtl8192cu

the software AP works immediately.

Kind Regards
Konstantin


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