Hey, > quite a while ago, I reported inconsistencies with Telit LE910Cx signal > quality query when using mbim (see > https://www.mail-archive.com/modemmanager-devel@lists.freedesktop.org/msg06990.html). > Now I had to get back to this issue, since our customers heavily complain > about the bad signal quality shown (although the connection is good and fast). > > While trying to find a solution I stumbled across the atds_signal_query > message and experimentally used it instead the signal_state_query mbim > message. The result is, that the signal quality is now much higher and > matches what we see when not using mbim (and matches what we see on the same > location using other LTE modems). > > So my questions are: > > Is there any documentation about the atds_signal_query command? I did not > find any.
ATDS is an AT&T specific extension that most manufacturers implement. I truly don't recall where I found it, but it is likely somewhere out there. > Do I have to expect problems when I prefer using atds_signal_query over > signal_state_query If you're doing a query, operation-wise it should be equivalent. > How to submit that change to modemmanager so that it can be used by others? Please note that you can also enable the "extended signal quality support" in the Signal interface. If you do that on a MBIM capable modem, it will default to use either Microsoft extensions service or otherwise the ATDS service. So there is already some support there if you want to use it. If you would like to change the default signal quality loading logic in MBIM so that it uses ATDS instead of the original MBIM service, this one is trickier, because, which one would you use? What if some other modem has the original MBIM command working better than the ATDS one? The ATDS one also lacks support for threshold configuration so no indication support, it is exclusively a polling-based operation which isn't ideal. I'd suggest you try with the Signal interface first to see if that fits your needs. Also, why would those values be so different? This is something Telit should probably investigate. > Should the command be used for this particular modem only, for all telit > modems or even for all mbim modems? (In the patch I currently use, I use that > command on all mbim modems that have the command available) > Is the patch completely removing the original method? Or do you apply the ATDS method instead of the original one for your device? Something like this could be gated via a new udev tag that modifies the default behavior (e.g. see ID_MM_QMI_CONNECTION_STATUS_POLLING_ENABLE for a similar thing with a different default behavior change in QMI modems).
