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Author Topic: Wifi Disconnects frequently  (Read 3491 times)

jakedempsey

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Wifi Disconnects frequently
« on: July 28, 2015, 08:49:40 AM »
I have installed the debian image: imx233_debian_3_11_wifi_RTL8188_AX8877_LAN9512_GPIO_2G_preliminary.  I have an imx233 micro and it boots and runs just fine but the wifi disconnects alot!  I can not figure out why.

I also have the MOD-WIFI-RTL8188 as the wifi module.

Has anyone experienced this? What was the solution?

Just as an aside: A reset of the device gets my connectivity back .
« Last Edit: July 28, 2015, 08:51:55 AM by jakedempsey »

lambda

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Re: Wifi Disconnects frequently
« Reply #1 on: July 28, 2015, 12:05:08 PM »
Hi,

this is difficult to guess without more information. Ie do you get any
dmesg output when this happens? Or any other logging output?
If not, how do you acutally know that wifi has disconnected?

I can only guess:
Your power supply might be insufficient?

HTH,
Harald

JohnS

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Re: Wifi Disconnects frequently
« Reply #2 on: July 28, 2015, 12:40:20 PM »
Check nothing is deliberately doing it e.g. for power saving.

John

jakedempsey

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Re: Wifi Disconnects frequently
« Reply #3 on: July 28, 2015, 07:17:54 PM »
I have added the power save config as found here:

http://linux-sunxi.org/Wifi#8192cu

That did not help.

I am using a 5V 1A power adapter which should be ample stable power.

I know that it has disconnected because I can even ping a host, or ssh into the machine, etc.  A restart solves the problem but of course that is not a solution.

I do not get any output printed in my serial session terminal when this occurs.  Would there be another place I could look to see log output of what occurred?

JohnS

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Re: Wifi Disconnects frequently
« Reply #4 on: July 28, 2015, 07:57:19 PM »
1A is not enough to power reliably in my experience, even if nothing else is connected (definitely no display, no hdd, etc).

John

jakedempsey

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Re: Wifi Disconnects frequently
« Reply #5 on: July 28, 2015, 08:20:11 PM »
I'll try a bigger power adapter.  However, the power consumption listed here for the micro is only .4 watts which would make a 5V 1A power supply plenty for the board right?

I have the MICRO
https://www.olimex.com/Products/OLinuXino/_resources/OLinuXino-Consumption.pdf

Also, I only have the usb wifi plugged in and I am using the debug uart to connect via serial-to-usb to my laptop. No monitor, no hdd.

lambda

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Re: Wifi Disconnects frequently
« Reply #6 on: July 28, 2015, 08:42:57 PM »
I know that it has disconnected because I can even ping a host, or ssh into the machine, etc.

That could be caused by many things and is no clear diagnostic at all.

Quote
  A restart solves the problem but of course that is not a solution.

Finding a way to fix this from software would provide some hints on what is
going wrong in the first place.

Obvious question: Does unplugging/replugging the wifi adapter help?

Quote
I do not get any output printed in my serial session terminal when this occurs.  Would there be another place I could look to see log output of what occurred?

Depending on the system configuration maybe not everything is logged to the console.
Try the command 'dmesg' to check if there are more kernel messages.
If userspace logs something that would typically be under /var/log/something but I
don't know if this is enabled on your system.

Other obvious things to check, that I can think of right now:
* Does the wifi adapter work reliably on other systems - ie your PC running linux?
* Is the adapter still registered on the USB bus after connectivity is lost? - Probably
  check this with lsusb, usbdump or some similar tool.
* What is the output of the various tools starting their name with "iw" (iwconfig, iwlist, etc.)

HTH,
Harald

jlumme

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Re: Wifi Disconnects frequently
« Reply #7 on: July 29, 2015, 06:15:41 AM »
We are using Ralink 2870 USB wifi dongle, and sometimes (quite infrequently, like once every 2 weeks) we have a problem that usb goes down and so does our wifi.

Check your system logs if you can see message like "ci_hdrc ci_hdrc.1: fatal error", this is what happens to us.
No workaround yet to this problem, and it's fairly infrequent that so far I haven't looked into it too much.
I'm considering watchdog to monitor network connectivity, and reboot the board if necessary..