| commit | 84b056a89d3c5b6cf6c5eeeafd4c4b14d6333aa9 | [log] [tgz] |
|---|---|---|
| author | Michael Riesch <michael.riesch@wolfvision.net> | Wed Jul 31 09:01:16 2024 +0200 |
| committer | David Gibson <david@gibson.dropbear.id.au> | Thu Aug 01 12:56:59 2024 +1000 |
| tree | 75dea5680fc7d2e8125232afb656e6e66345e60b | |
| parent | 1df7b047fe437708c70cbd2262557d19e40022a6 [diff] |
checks: relax graph checks for overlays
In device tree overlays, the following patterns occur frequently:
board.dts:
/dts-v1/;
/ {
display-controller {
ports {
#address-cells = <1>;
#size-cells = <0>;
vp0: port@0 {
reg = <0>;
vp0_out: endpoint {
};
};
vp1: port@1 {
reg = <1>;
};
};
};
};
overlay-endpoint.dtso:
/dts-v1/;
/plugin/;
&{/} {
hdmi-tx-connector {
port {
hdmi_tx_in: endpoint {
remote-endpoint = <&vp0_out>;
};
};
};
};
&vp0_out {
remote-endpoint = <&hdmi_tx_in>;
};
In this case, dtc expects that the node referenced by &vp0_out is
named "endpoint", but the name cannot be inferred. Also, dtc
complains about the connections between the endpoints not being
bidirectional.
Similarly, for a different overlay overlay-port.dtso:
/dts-v1/;
/plugin/;
&{/} {
panel {
port {
panel_in: endpoint {
remote-endpoint = <&vp1_out>;
};
};
};
};
&vp1 {
vp1_out: endpoint {
remote-endpoint = <&panel_in>;
};
};
dtc expects that the node referenced by &vp1 is named "port", but the
name cannot be inferred.
Relax the corresponding checks and skip the parts that are not reasonable
for device tree overlays.
Signed-off-by: Michael Riesch <michael.riesch@wolfvision.net>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The source tree contains the Device Tree Compiler (dtc) toolchain for working with device tree source and binary files and also libfdt, a utility library for reading and manipulating the binary format.
dtc and libfdt are maintained by:
A Python library wrapping libfdt is also available. To build this you will need to install swig and Python development files. On Debian distributions:
$ sudo apt-get install swig python3-dev
The library provides an Fdt class which you can use like this:
$ PYTHONPATH=../pylibfdt python3
>>> import libfdt
>>> fdt = libfdt.Fdt(open('test_tree1.dtb', mode='rb').read())
>>> node = fdt.path_offset('/subnode@1')
>>> print(node)
124
>>> prop_offset = fdt.first_property_offset(node)
>>> prop = fdt.get_property_by_offset(prop_offset)
>>> print('%s=%s' % (prop.name, prop.as_str()))
compatible=subnode1
>>> node2 = fdt.path_offset('/')
>>> print(fdt.getprop(node2, 'compatible').as_str())
test_tree1
You will find tests in tests/pylibfdt_tests.py showing how to use each method. Help is available using the Python help command, e.g.:
$ cd pylibfdt $ python3 -c "import libfdt; help(libfdt)"
If you add new features, please check code coverage:
$ sudo apt-get install python3-coverage $ cd tests # It's just 'coverage' on most other distributions $ python3-coverage run pylibfdt_tests.py $ python3-coverage html # Open 'htmlcov/index.html' in your browser
The library can be installed with pip from a local source tree:
$ pip install . [--user|--prefix=/path/to/install_dir]
Or directly from a remote git repo:
$ pip install git+git://git.kernel.org/pub/scm/utils/dtc/dtc.git@main
The install depends on libfdt shared library being installed on the host system first. Generally, using --user or --prefix is not necessary and pip will use the default location for the Python installation which varies if the user is root or not.
You can also install everything via make if you like, but pip is recommended.
To install both libfdt and pylibfdt you can use:
$ make install [PREFIX=/path/to/install_dir]
To disable building the python library, even if swig and Python are available, use:
$ make NO_PYTHON=1
More work remains to support all of libfdt, including access to numeric values.