What is the latest kernel release that support DB820c

It seems that there is no linaro folder under http://releases.linaro.org/96boards/dragonboard820c/ May I ask the reason? What is the latest release for DB820c? Does the latest kernel support CSI camera and hdmi on db820c? Many thanks.


HDMI definitely works. No idea about CSI – doesn’t offer me any incentive compared to UVC on USB3, which “just works”.

Hi doitright, Thank you for your reply. Does your wifi work as well with 5.7?

The wifi/bt chip is qca6174a. This is a pretty common chip that has been supported in mainline since forever. Same with the ethernet.

CSI driver should work (camss), with correct tuning of the device tree.

I would like to add a caveat to doitright’s comment ‘HDMI definitely works’. It does not work with my monitor. The last time it worked for me was with kernel 4.11 as described in this thread:

It has not worked since, but I did get a passive DVI to HDMI adapter to drive the monitor through the DVI input. This works on the HDMI output from my PC (as did the HDMI to VGA adapter) but, again, not on the DB820c. Perhaps I should check again that kernel 4.11 still works. Also, I have since had to buy a new monitor. My trusty Iiyama S902JT CRT, of 20 years standing, failed just two days into the recent lockdown but I did manage to get myself a fancy 32" UHD monitor. At some time I will see if the DB820c will drive it.

I have recently been using snapshot 550 which is based on kernel 5.4 so, after seeing doitright’s comment, I installed snapshot 678, which is based on kernel 5.7, but still no luck with HDMI. I was not surprised as it does not work with my own builds of 5.7 either.

With respect to the QCA6174, you might need the regulatory database and you might need to change to the upstream version rather than debian:

root@linaro-alip:~# apt-get install wireless-regdb
Unpacking wireless-regdb (2020.04.29-1) ...
Setting up wireless-regdb (2020.04.29-1) ...
update-alternatives: using /lib/firmware/regulatory.db-debian to provide /lib/firmware/regulatory.db (regulatory.db) in auto mode
root@linaro-alip:~# update-alternatives --display regulatory.db
regulatory.db - auto mode
  link best version is /lib/firmware/regulatory.db-debian
  link currently points to /lib/firmware/regulatory.db-debian
  link regulatory.db is /lib/firmware/regulatory.db
  slave regulatory.db.p7s is /lib/firmware/regulatory.db.p7s
/lib/firmware/regulatory.db-debian - priority 100
  slave regulatory.db.p7s: /lib/firmware/regulatory.db.p7s-debian
/lib/firmware/regulatory.db-upstream - priority 50
  slave regulatory.db.p7s: /lib/firmware/regulatory.db.p7s-upstream
root@linaro-alip:~# update-alternatives --config regulatory.db
There are 2 choices for the alternative regulatory.db (providing /lib/firmware/regulatory.db).

  Selection    Path                                  Priority   Status
* 0            /lib/firmware/regulatory.db-debian     100       auto mode
  1            /lib/firmware/regulatory.db-debian     100       manual mode
  2            /lib/firmware/regulatory.db-upstream   50        manual mode

Press <enter> to keep the current choice[*], or type selection number: 2
update-alternatives: using /lib/firmware/regulatory.db-upstream to provide /lib/firmware/regulatory.db (regulatory.db) in manual mode

Either yours is broken, or the only monitor you’ve tried with it is an obsolete heap.
For real? A CRT? I haven’t even SEEN a CRT in well over a decade. Probably closer to 2 decades.

The only thing I can find that describes that ancient thing’s specifications is this;

Interfaces: 5xBNC, D-SUB mini.

Sounds like ancient analog hardware that can’t possibly work.

A passive DVI-A to DSUB could drive it, but that requires a video card that has a DVI-A.
Hint: DVI-A is analog. DVI-D is digital and compatible with HDMI.

And just because you can make the plugs fit together does not mean that they are compatible.

Looking at my post again, I see that I did not make it clear which monitor I was referring to. You would need to look at the original thread I referred to to see DELL 1505FP. Although I did also try the Iiyama through the adapter cited in that thread, which also did not work, and so I presumed it was something to do with the active adapter.

A brief look at the datasheet for the Dell monitor shows that the connectors are VGA and DVI-D:

and, as I said in my first post, with the passive adapter plugged into the DVI-D port, the monitor works from the HDMI port of my PC.

This monitor was bought, some years ago at a jumble sale, for the princely sum of £1, for the sole purpose of acting as a spare, in the event of my main monitor failing, to enable me to order a new monitor online. Which purpose it fulfilled.

It is an appalling monitor and indicative of the LCD technology of its day. Indeed, it was only when 4k monitors became available that I considered it advantagious to switch from CRT to LCD and such monitors have only become affordable quite recently.

If you are too young to remember CRTs then you will not be aware of how poor the image quality of early LCDs was. Indeed, even now, my new monitor, a Benq PD3200U https://pcmonitors.info/reviews/benq-pd3200u/, suffers from the infamous IPS/AHVA glow in the bottom right corner but the additional real estate makes up, more than enough, for its LCD shortcomings and it has slightly higher DPI than the Iiyama, 140 against 135.
The following is a better reference for the Iiyama: