[Nexus 7 (2013) Android Development] Siggyceline:
Updated from unofficial LineageOS 14.1 to Official 17.1. I was already repartitioned, so no biggie.

- Downloaded and installed TWRP Flox.

- Download latest LineageOS nightly (02/08/2021)

- Magisk 21.4

- Gapps nano Android 10 ARM.

Cleared everything in TWRP except Media (where my downloads directory resides), and then installed...cleared Davik & cache afterwords.

Reboot and all is well. Restored from Google, Restored from my Nova backup.

All working as expected....Except for one thing, which is critical for me. I need DFS channels, and the WCNSS driver included in LineageOS (for a VERY long time now) does not include DFS support. I have a WCNSS driver that DOES support DFS, and have been using it (replacing the LineageOS 14.1 version) for a few years now:

I even made a post here previously about the "fix":

"Hi Folks,

One of the (many) reasons I chose to try Lineage, (or any custom ROM for that matter), was my desire to use my Nexus 7 2013 devices for Wi-Fi Analytics. As most here are probably aware, the challenge is that Stock Nexus 7 2013 FW does not support DFS at all. Anything on those DFS channels cannot be seen by either the Nexus 7 itself, or via 3rd Party apps (i.e., Wi-Fi Analyzer).

Anyway, after upgrading to Lineage 14.1, I found nothing really changed in that regard, and I still could not see DFS. I have Four APs for my Wi-Fi network, and two of them are operating 5GHz DFS channels. (I run CH 36, CH 100, CH132, and CH149, all 80MHz)

Knowing full well that the Qualcomm WCN3660 Wi-Fi chipset in the Nexus 7 2013 can support DFS, I went about investigating driver versions and configuration. After much trial & error, I found a solution.

(Assumes Rooted Lineage 14.1 installed already)

1.) Download "WCNSS_qcom_wlan_nv.bin" driver from here:

firmware_bin - platform/vendor/qcom-opensource/wlan/prima - Unnamed repository

source.codeaurora.org

2.) On rooted Lineage 14.1 Nexus 7 goto:

/vendor/firmware/wlan/prima

3.) Rename "WCNSS_qcom_wlan_nv.bin" to "WCNSS_qcom_wlan_nv.bin.old"

4.) Copy the file you downloaded to this same directory (/vendor/firmware/wlan/prima)

5.) Reboot

6.) Enjoy DFS channels

It appears the WCN3660 driver from the source above (CodeAurora) is newer than the driver being used in Lineage 14.1. Don't know if there is some other reason why the choice was made to use the old driver from 2008, but this newer version works great on my devices, and now allows DFS channels.

Just my 2 cents. I looked all over the forums for a solution to this issue, and never found anything. I also spent a LOT of time trying to edit the WCNSS_qcom_cfg.ini file (often in the WRONG Location!), to no avail. Decided to post the working solution I found so others may (hopefully) benefit from my findings.

(NOTE: if you try to use the WCNSS_cfg.dat or WCNSS_qcom_cfg.ini files from the CodeAurora web site, it is most likely Wi-Fi on your Nexus 7 2013 will not start...at all. In my case, (and on both of my devices [flo & deb]) I found it necessary to ONLY replace the WCNSS_qcom_wlan_nv.bin driver file. The other two ORIGINAL files seem to work fine with the newer driver. )

Siggy"

So....this fix doesn't work with Lineage17.1 (Android 10), as apparently something is changed where, (even when rooted with Magisk), it is not possible to copy files to /vendor/firmware/wlan/prima with either Root Explorer or from TWRP. (In fact, TWRP doesn't even show any files in the directory).

OK, so Google changed something around this in Android 10? Is that correct?

Assuming so, does anybody know an easy work-around so I can easily replace the WCNSS_qcom_wlan_nv.bin ? I was good doing it simply from Root Explorer in LineageOS 14.1. This made it a tolerable quick process every time I might update the ROM. Having to get into terminal and type a bunch of stuff every-time I update 17.1 to a new build is probably not going to be acceptable to me. Rebuilding my own custom ROM every time also is not gonna be cool.

So the question is, does anybody know a way to do this easily and consistently for Android 10 (LineageOS 17.1), or do I need to go back to LineageOS 14.1 Unofficial? (The guy hosting 14.1 unofficial weeklies just pulled his site due to some leeches....so that is why ended up searching for alternatives and found the official Lineage 17.1). I have 4 DFS AP's in my production environment, and need DFS support. (Plus I use several network scanning apps on my Nexus 7 to see RF spectrum, and without the proper driver, those apps will not even show any DFS channels...which makes the Wi-Fi tools useless...)

Thanks for any/all feedback...

Siggy