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> rtl8192cu vs 8192cu on RPi
Posted by prox, from Seattle, on June 22, 2017 at 02:06 local (server) time

From the RPi annoyances department..

I did a kernel upgrade on one of my Raspberry Pis earlier today by installing the latest raspberrypi-kernel from testing (1.20170515-1).  It installed Linux 4.9.28+ and I instantly realized there was something wrong since the Wi-Fi was very latent and would periodically disconnect from any nearby WAPs.  I use the Edimax EW-7811u USB stick since this Raspberry Pi is one of the original model Bs without Wi-Fi.

After debugging a bit and searching the Internet it appeared that I was now using the wrong driver, rtl8192cu instead of 8192cu:

(henry:22:18:PDT)% uname -a
Linux henry 4.9.28+ #998 Mon May 15 16:50:35 BST 2017 armv6l GNU/Linux
(henry:22:19:PDT)% lsmod|grep -i rtl
rtl8192cu              79230  0
rtl_usb                12234  1 rtl8192cu
rtl8192c_common        57894  1 rtl8192cu
rtlwifi                85339  3 rtl_usb,rtl8192c_common,rtl8192cu
mac80211              650547  3 rtl_usb,rtlwifi,rtl8192cu
cfg80211              525710  2 mac80211,rtlwifi

Apparently, before this upgrade the 8192cu driver was being used.  So, I added "blacklist rtl8192cu" to /etc/modprobe.d/raspi-blacklist.conf and rebooted.  Bingo, the right module is now being used:

(henry:23:04:PDT)% lsmod|grep 8192
8192cu                597868  0
cfg80211              525710  1 8192cu

No more Wi-Fi drops!

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