r8188eu driver in 5.15 only shows wifi networks on channel 11

Zameer Manji
2021-11-05T04:35:15Z

Hello,

I am reporting a regression in 5.15 in the r8188eu driver. Apologies
if this is not the right mailing list to report the issue, I am not
sure if reporting issues in staging drivers is appropriate for
linux-wireless list.

I have a TP Link TL-WN725N device [0]. With 5.14 it is able to connect
to my wifi network and operate as expected. With 5.15 it is not able
to, the root cause appears that the wifi network no longer shows up in
`iwlist wlan0 scanning`. Here is the entry that shows up in 5.14 but
not in 5.15:
```
Cell 01 - Address: A0:40:A0:85:B9:FA
ESSID:"WIFI.-SLOW"
Protocol:IEEE 802.11bgn
Mode:Master
Frequency:2.447 GHz (Channel 8)
Encryption key:on
Bit Rates:144 Mb/s
Extra:rsn_ie=30140100000fac040100000fac040100000fac020c00
IE: IEEE 802.11i/WPA2 Version 1
Group Cipher : CCMP
Pairwise Ciphers (1) : CCMP
Authentication Suites (1) : PSK
IE: Unknown:
DD7D0050F204104A0001101044000102103B000103104700105AAA8B8AF2347DC2798F056F8BC933551021000D4E4554474541522C20496E632E10230006523730303050102400065237303030501042000233321054000800060050F204000110110006523730303050100800022008103C0001031049000600372A000120
Quality=100/100 Signal level=100/100
```

The only networks that show up in `iwlist wlan0 scanning` in 5.15 have
`Frequency:2.462 GHz (Channel 11)` networks on other channels do not
show up.

I don't have any kernel parameters set, and I am using the same
firmware for both kernels. If it matters, the kernels were taken from
Ubuntu's Mainline PPA [1].

Full output from lsusb for this device.

```
Bus 003 Device 002: ID 0bda:8179 Realtek Semiconductor Corp.
RTL8188EUS 802.11n Wireless Network Adapter
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x0bda Realtek Semiconductor Corp.
idProduct 0x8179 RTL8188EUS 802.11n Wireless Network Adapter
bcdDevice 0.00
iManufacturer 1 Realtek
iProduct 2 802.11n NIC
iSerial 3 00E04C0001
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0027
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xa0
(Bus Powered)
Remote Wakeup
MaxPower 500mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x03 EP 3 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
```

Related dmesg output in 5.15
```
[ 13.542110] r8188eu: module is from the staging directory, the
quality is unknown, you have been warned.
[ 13.570753] Chip Version Info:
CHIP_8188E_Normal_Chip_TSMC_D_CUT_1T1R_RomVer(0)
[ 13.623399] EEPROM ID = 0x8129
[ 13.646796] usbcore: registered new interface driver r8188eu
[ 14.416673] R8188EU: Firmware Version 11, SubVersion 1, Signature 0x88e1
[ 15.484020] R8188EU: INFO indicate disassoc
```

Please let me know if any other information is needed in root causing
this bug, or if this bug should
be directed elsewhere.

[0] Available here
https://www.amazon.com/TP-Link-wireless-network-Adapter-SoftAP/dp/B008IFXQFU/
[1] https://kernel.ubuntu.com/~kernel-ppa/mainline/
--
Zameer Manji