How reliable is the modem?

Hardware Librem 5
8

Thanks for this. I have set it up on my Pinephone so I know how to setup MMS, just making sure everything worked!

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9

When driving in a car, the modem has difficulty transitioning from one cell tower to the next, causing any streaming data to stop. So if you are streaming music while driving, frequently the music will stop and you have to reset the modem. This is a longstanding, frustrating deficiency, and I don’t know if a fix will ever come.

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10

This isn’t in any way to detract from your issue Zimmy, just dropping in to comment that I have been driving and streaming for 5+ weeks now with no issue. I am curious how many others have this issue and whether or not there is a solution to the problem.

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11

I’m remnded of the old Bell Telephone policy on modem reliability, no modem was guaranteed above 300bps!

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12

I have the BM818-A1 modem on T-Mobile with up-to-date modem firmware and up-to-date Byzantium. The data drop-outs happen so frequently I don’t bother streaming while driving anymore. Too frustrating.

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13

That’s because of a bug in the kernel that causes it to suspend the USB bus. This is not just isolated to you. You can fix it by running this on boot (every boot… though you could probably make it run on startup): echo 'on' | sudo tee /sys/bus/usb/devices/1-1.2/power/control

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14

cron has a special time of @reboot for startup so yeah a cron job with that schedule should work.

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15

Oh wow, interesting. Thanks for dropping into all the threads to post this. Interesting. Zimmy / Xeda, does that help you guys?

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16

I will try it for a week and report back.

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17

My first modem was the Texas Instruments modem chipset, a speaker and a mic in yogurt cups with the telephone receiver placed into said cups. Dialed into the BBS and it worked. As a teenager I was so pumped it worked. Of course you could read way faster than 300 baud, but that was my first foray into going on the line…literally…lol.

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18

Is the suspension a bug, or rather a badly implemented power-saving feature? The default setting for that USB power control is “auto”, which sounds as though the power should come on when needed. Evidently it doesn’t reliably do so, and your fix does put a stop to the modem suspensions.

Should the developers look at making the auto setting more reliable? It seems a good idea to shut off the power when it is not needed, but obviously it should also turn on again at the right time.

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19

SMS was unreliable for me for a while, but now works great.

MMS still does not seem 100% reliable.

LTE is requires a workaround to work reliably. It will disconnect multiple times per day for me and I need to manually switch the modem off and on (via hardware kill switches) to get it to work again. But, after doing this whenever I have any internet issue I have no trouble using its internet all day all across the greater Los Angeles area, other than the very annoying periodic restarts needed.

Edit: Looks like @Aberts10 has a fix in this very thread!

Now I just need to figure out how to set up the cron job to run this upon reboot rather than needing to manually run echo 'on' > /sys/bus/usb/devices/1-1.2/power/control as root…

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20

cron supports the special string @reboot instead of the first five fields.

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21

I was mistaken in posting about a test which seemed to be successful but now I find to be otherwise. This post is withdrawn in its entirety.

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22

Right this way?

login as root and modify crontab to:

@reboot echo ‘on’ | /usr/bin/tee /sys/bus/usb/devices/1-1.2/power/control

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23

The crontab entry does not work, not even it does work on shell:

purism@pureos:~$ echo ‘on’ | sudo /usr/bin/tee /sys/bus/usb/devices/1-1.2/power/control
‘on’
/usr/bin/tee: /sys/bus/usb/devices/1-1.2/power/control: Invalid argument

Any ideas?

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24

On the shell I nailed it down: the ' chars have been due to cut and paste some UTF-8 chars.

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25

and specifically should not turn off while any data modem is supposedly turned on, even if there is momentarily no modem activity.

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26

For root the crontab entry does not get executed. Don’t know why.

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27

Running any cron job for user root gives in ´/var/log/syslog`:

Feb 18 16:47:01 pureos cron[488]: (*system*) RELOAD (/etc/crontab)
Feb 18 16:47:01 pureos CRON[5410]: Authentication failure
Feb 18 16:47:01 pureos cron[5410]: Authentication failure

which must have todo with root somehow being locked on the L5.
@dos, any idea how to make this working?

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