olerem
commented
7 years ago All REG related commands go over EP3 and EP4. This EPs was configured for some time as Bulk, then i added patches to revert this behavior back to Interrupt mode. Latest kernel and FW should include some optimization for this EPs. Which kernel version and FW versions are you using, do this changes applied or not? I can imagine different usb related issues:
- not enough power
- not enough usb bandwidth, especially if Bulk used instead of interrupt.
- bad usb signal, too long cable or bad connector
I assume, it should be possible to reduce this problems by mowing as match functionality as possible to the FW. So we avoid direct REG read/write operations.
Currently without FW changes, you can reduce EP3/EP4 load by disabling LED and bgscan, if this are enabled.
rodizio1
erikarn
SunilMohanAdapa
melyux
sumeetkpatel
vk-gst
psyborg55
dagf2101
I've beeen trying to narrow this issue down for months now, but it's so weird, really don't know what to do further. Already tried disabling LED blinking, but that didn't seem to help much.
Sometimes cards don't get initialized, sometimes they do, but don't receive packets, sometimes they do and receive packets only for a second or two then they crash.
When this occurs, packet reception stops, ifconfig RX bytes/packets does not increase anymore.
Tried to unload the ath9k module, this seems to have crashed the whole USB subsystem, my ssh connection is gone and keyboard also doesn't work anymore.
It doesn't occur always and sometimes the REGISTER READ FAILED message don't seem to cause issues, here it looks like two of the three cards don't work:
But actually, only the first card doesn't work (5.3MiB received vs. 200MiB received):
Next test I wanted to do was to check if setting the cards in promiscous mode has something to do with it, rebooted and tried:
iwconfig wlan0 mode monitor ifconfig wlan0 up
Now the USB subsystem seems frozen again.
Next try was to only disable the packet reception in my startup script. Rebooted, now I cannot get three cards to work anymore at all. It always hangs while initializing the cards (bringing them up and into monitor mode on the desired channel).
The weird thing is, nothing regarding the wifi cards was changed, just commented out a line in a script that runs way after the initialization of the wifi cards. I know this sounds not logic at all, but I've had such weird behaviour on different occasions. It seems that just changing something completely unrelated makes a difference. Not sure why, maybe because some stuff gets loaded or executed with a few nano or milli-seconds different when files have changed on the sdcard?
Users of my EZ-Wifibroadcast image also reported similar things, some had problems with a newer version although they did not change anything with their hardware or setup and I did just some scripting cleanups and cosmetic stuff, i.e. nothing that would affect the wifi cards at all.
One user reported he could trigger that behaviour just by choosing a different channel, which also seems to make no sense at all.
I also could find forum posts from users trying to use more than two Atheros sticks from more than a year ago, they suffered the same problems.
Next test again with two cards. This time I can succesfully bring them up and issue "ifconfig wlan0 promisc".
Now the weird thing is, when I set the cards to promiscous mode via ifconfig, it seems to always trigger that REGISTER_READ_TIMEOUT message. However, sometimes the card is still able to receive packets, even though the message appeared. After running "ifconfig wlan0 promisc" a few times in a row though, it certainly stops working.
I can also trigger this with only one card. I.e. start-up the system, configure card, run "ifconfig promisc" for maybe 5-10 times and the card crashes.
Some general infos:
It seems to get worse with more cards: Two cards seem to work in 99.9% of cases, three cards in maybe 10%.
Can be reproduced with TPLink 722N/Alfa AWUS036NHA (both AR9271) and TPLINK 822 V2 (AR9287)
It seems related to other stuff using the USB bus. If the ethernet connection on the Pi is in use (which is also connected via USB internally), three cards almost never work.
The same happens with other wifi cards (rt2800usb). 1x ath9k_htc plus 3x rt800usb works, 2x ath9k_htc plus 1x rt2800usb is flaky. 2x ath9k_htc plus 2x rt2800usb is even more flaky.
However, 4x rt2800usb without any Atheros cards is absolutely stable and works 100%.
4x Atheros cards never work, not at all. Even when plugging them each after another, the 4th one always causes all kinds of crashes and issues
When plugging the cards slowly each after another (instead of having all three connected during boot-up), chances to get them working seem to be higher, but it doesn't always work.
It seems to have gotten worse since I changed Kernel timer frequency to 1000Hz (in order to fix a different problem with packets being delayed on the USB-Bus or subsystem somewhere).
It is not power-related or bad cables or something, I have even gone so far as soldering the adapters directly to the Raspberry USB Ports and powering the Pi and the cards directly from a 7.5 Ampere power supply connected to a large Lipo battery. Problem remains.
The problems only occur during initialization of the cards or a few seconds after the startup of the rx program which puts the cards into promiscous mode. If the cards have "survived" past that, they run stable for hours or even days. But just killing and re-starting the rx program (or issuing "ifconfig wlan0 promisc") can make them crash again anytime.