easytarget-MQ-Pro-IO/build-trees/README.md

# NOTE
# Being refactored at the moment. I want to make sure the dtsi and generic image are taken for currnet kernel;

## Preparation / requirements

### Compile and make tooling
You need `build-essential` installed:
```console
apt install build-essential`
```
*This will take a while.. as will most commands described here!*

By default the Device Tree compiler (`/usr/bin/dtc`) should already be installed in Ubuntu server, as should the linux-headers for the kernel.

### Enable source repos:
As root edit the file: `/etc/apt/sources.list.d/ubuntu.sources`

There should be two repo definitions, find the lines in them that say:
```console
Types: deb
```
And add `deb-src` so it now says:
```console
Types: deb deb-src
```
Save and exit editor.

Run
```console
sudo apt update
```
You should see a load of new (source) repos being updated, it is slow, let it finish.

## Install the linux sources
This can be done as a normal user
- Note that the command used here `apt source` will download the sources to the current working folder, not a fixed location.

We download the sources into the [sources](../sources) repo in this folder:
```console
cd source
apt source linux-riscv
```
Go for a coffee.. unless you are a developer you can ignore the 'git clone' suggestion.
- This will use ~1.6Gb of space.. so be prepared.

# Updating sources
If you re-run the command in this folder it will only download and update as needed, but is still somewhat slow since it verifies the existing downloads when updating.

----------------------------------------------------
# Rebuild dts tree for MQ pro..

### The following is wrong! It will be updated asap
```
Start by `cd`'ing into this [device tree](device-tree) folder and editing your device tree.

You can use the generic `sun20i-d1-mangopi-mq-pro.generic.dts` already in the device tree folder as a basis, or start with one of the ones provided with my precompiled trees.

You may also need to modify `sun20i-d1.dtsi` since this is where pin mappings are declared; eg UART pin sets are defined in this include file and then used in the main tree file.

A full-on tutorial for device tree editing is far beyond the scope of both this document and author.
```

#### Terms
* `.dts` is a top-level Device Tree Source file.
* `.dtsi` is a include file for the `.dts`
* `.dtb` is the binary compiled device tree, this is what we are building here, and is supplied to the kernel at boot time.

## Building the MQ PRO device tree (`.dtb`)

## Compile the mq-pro dts with the current kernel headers
<Describe `make-trees.sh`>

-----------------------

# Test Installing self-built DTB's

### Move dtb into the boot tree
* move the `.dtb` file into the `/boot` folder:
  `sudo mv dtb-6.8.0-31-mqpro-generic /boot/dtbs`
* make a soft link in `/boot` to this:
  `sudo ln -s dtbs/dtb-6.8.0-31-mqpro-generic.dtb /boot/dtb-mqpro`

### Set up Grub to test boot the new DTB
Initially we will test the new dtb:
* backup the grub config: `sudo cp /etc/grub/grub.cfg /etc/grub/grub.cfg.generic-dtb`
* `sudo vi /etc/grub/grub.cfg`  (or use nano if you prefer)
  Find the 1st `menuentry` section (the default Ubuntu one) and edit the `devicetree` line to look like:
  `devicetree      /boot/dtb-mqpro`
* Reboot (`sudo reboot`) (remember the mq-pro is sloooow to reboot ;-) )
* If the reboot fails you can either attach a serial adapter to the GPIO pins and select the fallback kernel from the advanced options menu, and then restore the grub config backup once logged in. 
  Or (if no serial available) remove the SD card, mount it on another computer and restore the file there.

### Quick check that we have the correct device tree!
`dtc -I fs /sys/firmware/devicetree/base | grep 'model'`
* ignore all the 'not a phandle reference' warnings
* you should see `model = "MangoPi MQ Pro"` at the end

----------------------------------------------------
## Pin Map tool
After rebooting you can run **list-pins.py** (see below) to verify the new mappings.

If you have errors rebooting (maybe a corrupt file if you rebuilt it etc..) you need to either boot using a USB serial adapter on the console pins and select the recovery image,  or, in grub, edit the command and revert to the generic `/boot/dtb`.
As a last resort you may have to remove the SD card, mount the `/boot` partition and edit `grub/grub.cfg` there.
* !! The 'default' dtb supplied by ubuntu should always be softlinked as `/boot/dtb`, so putting `devicetree      /boot/dtb` in grub in place of the custom `.dtb` should work and is predictable (no version numbers etc).

## Examining the DTB pin mappings:
In the [tools](../tools) folder there is a python script called `list-pins.py`.

To run the pin list tool you need to be in the tools directory, then run:
```console
python3 list-pins.py MangoPi-MQ-Pro
```
* The script requires root acces (via sudo) to read the pin maps.
* Running the script produces the same map I use in this documentation.
* The data used to assemble the `.gpio` map files identifies which interface a pin is attached to, but not it's specific function for the interface.
  * eg it can say 'pinX and pinY are mapped to UART2', but cannot identify which pin is the TX and which is the RX; a limitation of the data, my apologies..
  * You therefore need to reference the [D1 pin mapping table](../reference/d1-pins.pdf) to get the exact functions for pins when running this for yourself.
* The README files uploaded for alternate device trees *have been manually edited* to note full pin function for convenience.
-----------------------------------------------------

# Making Permanent:
<this needs expanding/fixing>
<can we do this via flash-kernel? it appears to have an 'override' dtb file config. ?????>

## Old method

(As Root) Edit: `/etc/grub.d/10_linux` line 458 to say:
```
  for i in "dtb-mqpro" "dtb-${version}" "dtb-${alt_version}" "dtb"; do
```

Note that we are adding `dtb-mqpro` to the start of this list, this is the 'search list' for the DTB files, the full section reads:
```bash
  dtb=
  for i in "dtb-mqpro" "dtb-${version}" "dtb-${alt_version}" "dtb"; do
    if test -e "${dirname}/${i}" ; then
      dtb="$i"
      break
    fi
  done
```
When Grub next rebuilds it *should* make the new DTB the default for all entries now. (this is untested, as of this writing there have not been any kernel upgrades to test them on)


# references/links:
https://manpages.ubuntu.com/manpages/focal/man1/dtc.1.html
https://forum.armbian.com/topic/29626-mango-pi-mq-pro-d1-device-tree-try-to-okay-serial/
https://github.com/torvalds/linux/tree/master/arch/riscv/boot/dts/allwinner
https://github.com/ners/MangoPi/tree/d2589d8211a2f9ae57d88f2e2c4d6a449d668f9e/MangoPi/linux/arch/riscv/boot/dts/allwinner
DTS version that is used in the official armbian image?
https://github.com/smaeul/u-boot/tree/329e94f16ff84f9cf9341f8dfdff7af1b1e6ee9a/arch/riscv/dts