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wlan-prima (wireless module) and wcnss-service

Continuation of https://github.com/postmarketOS/pmbootstrap/issues/143 and https://github.com/postmarketOS/pmbootstrap/issues/358

@yuvadm and I are working (see my titan-wifi branch and yuvadm's device-mozilla-flame) on the dynamic firmware loading feature (https://github.com/postmarketOS/pmbootstrap/issues/147) which is required by the wlan-prima module to load blobs (are these considered blobs?) in order to initialize the wireless interface later. This is the case for mozilla-flame and motorola-titan so far.

This is how it works:

I made the wcnss-service (initially written for Android) some modifications (removed Android stuff, mocked Android functions) and added a Makefile and now it compiles and works in real linuxes.

This so-called service reads the following system variables:

  • ro.serialno
  • ro.baseband (the MODEM_BASEBAND_PROPERTY constant)

and writes wlan.driver.config and wlan.driver.ath.

Maybe writing the variables is not needed for postmarketOS. However ro.serialno is used to generate a serial number, used to initialize the interface. I have hardcoded this value for testing but it can be read from /proc/cmdline.

However my device gets frozen right after running wcnss-service. There must be something I've left back.

Things we should take the chance to discuss:

  • Firmware path(s). Is it /lib/firmware or /lib/firmware/postmarketos?

yuvadm commented on Matrix:

also keep in mind that at least for the flame I have firmware that is flashed on some special partitions and ideally i would want to mount them to /lib/firmware/$foo

This is a draft TODO:

  • udev dynamic firmware loading https://github.com/postmarketOS/pmbootstrap/issues/143 (pick firmware.sh and the udev rule from some of the branches and include them in postmarketos-base
  • Fix wcnss-service so that it doesn't hang the device :)
  • Investigate also other versions of wcnss-service (will paste the link later, I found some newer version, that might fix the hang) and compiling options (is -DWCNSS_QMI needed?)
  • Research what does the serial number (derived from ro.serialno). Is this the MAC address?
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