| commit | 9cabae6b0351dff7eb634ebcdcabf06a276c1222 | [log] [tgz] |
|---|---|---|
| author | Jon Hunter <jonathanh@nvidia.com> | Wed Jul 09 15:24:52 2025 +0100 |
| committer | David Gibson <david@gibson.dropbear.id.au> | Thu Jul 10 19:09:39 2025 +1000 |
| tree | e84489359fd6ce3fbc7fde41a04e9356468d945f | |
| parent | 605dc044c3fef39fe5404d40f2b5569d77916339 [diff] |
checks: Fix detection of 'i2c-bus' node
If an I2C controller has a 'i2c-bus' child node, then the function
check_i2c_bus_bridge() does not detect this as expected and warnings
such as the following are observed:
Warning (i2c_bus_bridge): /example-0/i2c@7000c000: \
incorrect #address-cells for I2C bus
Warning (i2c_bus_bridge): /example-0/i2c@7000c000: \
incorrect #size-cells for I2C bus
These warnings occur because the '#address-cells' and '#size-cells' are
not directly present under the I2C controller node but the 'i2c-bus'
child node. The function check_i2c_bus_bridge() does not detect this
because it is using the parent node's 'basenamelen' and not the child
node's 'basenamelen' when comparing the child node name with 'i2c-bus'.
The parent node's 'basenamelen' is shorter ('i2c') than 'i2c-bus' and so
the strprefixeq() test fails. Fix this by using the child node
'basenamelen' when comparing the child node name.
Fixes: 53a1bd546905 ("checks: add I2C bus checks")
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Message-ID: <20250709142452.249492-1-jonathanh@nvidia.com>
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.