How to compile kernel in Yocto to contain rtl8192cu driver?

[ShawnHymel]

I have an old Edimax EW-7811Un that I am trying to get working on the STM32MP157D-DK1. I have installed Yocto along with poky and the meta-st-stm32mp BSP layer. I do not want to use OpenSTLinux right now.

I configured the kernel with

bitbake -c menuconfig virtual/kernel 

and made sure the following kernel modules were enabled:

• Networking support > Networking options (following should be enabled):
  • [*] TCP/IP networking
    • [*] IP: kernel level autoconfiguration
      • [*] IP: DHCP support
      • [*] IP: BOOTP support
      • [*] IP: RARP support
    • <*> The IPv6 protocol
• Networking support > Wireless
  • <M> cfg80211 - wireless configuration API
  • [*] cfg80211 wireless extensions compatibility (for compatibility with some older tools, e.g. get iwconfig to talk to device)
  • <M> Generic IEEE 802.11 Networking Stack (mac80211)
  • [*] Minstrel (for rate control in 802.11)
• Device Drivers > USB support, make sure USB Host is enabled:
  • <*> Support for Host-side USB
  • [*] Enable USB persist by default
• Device Drivers> Network device support > Wireless LAN
  • <M> Realtek rtlwifi family of devices
    • <M> Realtek RTL8192CU/RTL8188CU USB Wireless Network Adapter
    • [*] Debugging output for rtlwifi driver family

I added the following line to the end of conf/local.conf:

IMAGE_INSTALL += “linux-firmware-rtl8192cu�?

I built an image with:

bitbake core-image-minimal

However, it does not seem that the rtl8192cu module was included. I checked the manifest file with:

cat tmp/deploy/images/stm32mp1/core-image-minimal-stm32mp1.manifest | grep rtl

Nothing shows up, which should indicate that the rtl8192cu module was not included in the build, right?

I tried flashing the image to an SD card and booted up the board. I plug in the USB WiFi dongle and dmesg does not show that the driver is loading.

What am I missing to make this driver work?

[Kevin HUBER · Accepted solution]

Hi @ShawnHymel​ 

I don't know if you are still facing this problem, but maybe your issue is related to your kernel configuration.

In your linux configuration, the driver RTL8192CU is enabled as a Module (M means module), so you have to load the module.ko manually.

Device Drivers> Network device support > Wireless LAN

• <M> Realtek rtlwifi family of devices
  • <M> Realtek RTL8192CU/RTL8188CU USB Wireless Network Adapter
  • [*] Debugging output for rtlwifi driver family

You can check if your module is loaded by using the command:

lsmod | grep "rtl"

To build and "load" the driver by default, you have to enable it in the linux configuration, please switch:

• <M> Realtek RTL8192CU/RTL8188CU USB Wireless Network Adapter

to

• <*> Realtek RTL8192CU/RTL8188CU USB Wireless Network Adapter

Hope it help,

Regards,

Kevin

[Kevin HUBER]

Hi,

You can find more information about the menuconfig on the wiki: https://wiki.st.com/stm32mpu/wiki/Menuconfig_or_how_to_configure_kernel#Menuconfig_and_Developer_Package

Regards,

Kevin