Oh forgot to mention on the hardware side I'm powering the BBB with a 5V 10amp supply so there should be no power issues at all (it's a bit of a monster supply).
On Friday, August 22, 2014 12:10:00 AM UTC-7, Tony DiCola wrote: > > Hey all, I've been trying to track down why my wifi dongle doesn't work > reliably on boot and think I've narrowed it down to the drivers in the > official Debian 3.8 kernel being old and buggy. > > First, the hardware I'm using: > - Rev C BeagleBone Black, running the official Debian image from here: > http://beagleboard.org/latest-images > (side question, is the 5-14-2014 image on that page really the most recent > official Debian build?) > - Wifi dongle is an Edimax 7811Un, which is a RTL8192CU chipset. Very > popular and works perfectly with a Raspberry Pi. > - Yes I'm aware of the HDMI ground and power plane issue with wifi > dongles, I have the wifi dongle attached to a small USB hub that moves it > away from the BBB. > > My problem is that the wifi connection never reliably starts on boot. I > always have to log in and run ifdown wlan0 & ifup wlan0 to get it to > connect. My /etc/network/interfaces is configured in the standard way to > access my AP (exactly how I've configured Raspberry Pi's which work fine), > and for completeness the block of config looks like: > > # WiFi Example > auto wlan0 > allow-hotplug wlan0 > iface wlan0 inet dhcp > wpa-ssid "my AP name" > wpa-psk "my password" > > I ran some experiments to reboot the BBB (just using the reboot command) > multiple times and count how often the wifi connection would come up > successfully on boot. The results were not good, here's what I saw: > - With "auto wlan0" and "allow-hotplug wlan0" in /etc/network/interfaces 6 > out of 13 attempts succeeded: success rate of 46%. > - With only "auto wlan0" in /etc/network/interfces 8 out of 13 attempts > succeeded: success rate of 62%. > - With the dongle connected directly to the USB port (i.e. not through the > hub) only 4 out of 13 attempts succeeded: success rate of 31%. > > I did all I could to find any information from dmesg and syslog for the > failed attempts, but there's no info there. When the connection works on > boot I see messages about the RTL8192CU module and then the wlan connection > coming up. When the connection does not work I see the same messages about > the RTL8192CU module but none of the wlan connection messages. There are > no errors or failures at all in the log. It really feels like a timing or > internal issue with the RTL module. If there is some other log I should be > looking at please let me know and I will check it out. > > For comparison I ran the same test with the same wifi adapter on a > Raspberry Pi running the latest Raspbian OS image. It worked fine and > brought the wifi connection up all 13 times, success rate of 100%. > > At this point I was really confused why the BBB could not reliably bring > up a wifi connection at boot. Looking a little closer the big obvious > difference between the BBB and Pi is the kernel version. On the Pi it's > using kernel 3.15.3 whereas the BBB is running the 3.8 kernel. Looking at > the RTL8192CU source on kernel.org I can't find the 3.8 kernel source, > but at least comparing the 3.10 kernel to mainline there are quite a few > fixes in the more recent kernels but not in the older ones. > > To really confirm it was the 3.8 kernel I used Robert Nelson's upgrade > script to take my BBB to the 3.15.10-bone7 kernel (script from here > https://rcn-ee.net/deb/wheezy-armhf/v3.15.10-bone7/). After upgrading > the kernel I ran the same reboot test and surprise, surprise the BBB > brought up the wifi connection 13 out of 13 times, success rate of 100%. > > So long story short it seems like at least for Realtek adapters the > official Debian image's 3.8 kernel has some serious issues. I'm curious is > this a known issue or something being worked on right now? > > I noticed on the BBB kernel github there was just recently a commit > yesterday to add perhaps a backport of later RTL8192CU drivers to the 3.8 > kernel (looking at > https://github.com/beagleboard/linux/tree/3.8/drivers/net/wireless/rtl8192cu > ). Is this true that later RTL wifi drivers are being ported back to the > 3.8 kernel? > > Finally, is there any suggestion for what folks who use the RTL8192CU or > other RTL wifi adapters should do to use them right now on the BBB? Is the > 3.15.10-bone7 kernel stable enough for normal use? (like using GPIO, > loading and unloading device tree overlays, etc) > > For better or worse the Realtek wifi adapters are quite common (folks like > Adafruit only sell Realtek wifi adapters because they are known to work > with the Pi) and many folks coming to the BBB from the Pi are likely trying > to use them. I have a feeling many of the issues people have getting wifi > to work with the BBB are related to problems with the 3.8 kernel driver. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
