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[2003:d1:ff28:8200:39a2:a828:22a8:2fc5]) by smtp.gmail.com with ESMTPSA id w2sm1248704ejc.109.2020.11.20.07.52.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Nov 2020 07:52:38 -0800 (PST) From: Sebastian Fricke To: libcamera-devel@lists.libcamera.org Date: Fri, 20 Nov 2020 16:52:34 +0100 Message-Id: <20201120155234.29903-1-sebastian.fricke.linux@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH v4] Documentation: Add descriptions for env. variables X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" Describe the environment variables used in libcamera, excluded variables are `LIBCAMERA_IPA_FORCE_C_API` and `LIBCAMERA_IPA_PROXY_PATH`, the former because it is likely to be removed and the later because it has no current use-case. Add a brief explanation for the IPA configuration and IPA modules. List all the available Log levels and categories and add a short guide on how to use them for debugging. Signed-off-by: Sebastian Fricke Reviewed-by: Jacopo Mondi Reviewed-by: Kieran Bingham --- Changes since V3: * Rework the LIBCAMERA_LOG_LEVELS explanation * improve wording at various places * Move the changelog out of the commit description into the email Changes since V2: * replace bullet point list with definition list * Remove the category list as it is too difficult to maintain, instead explain how the categories are set with the LOG_DECLARE_CATEGORY & LOG_DEFINE_CATEGORY macros * Remove the short summary for the IPA module, as it can be misleading and probably not accurate enough * Improve the notes for debugging part by linking to a full explanation while extending the description in the documentation as well * Add an example for the Log level setting * Remove the documentation from guides and add it to the documentation base path Changes since V1: * abandon the usage of tables as they are too clunky and difficult to maintain * Fix a wrong example that does not work on most distributions and setups * Improve structure of log categories --- Documentation/environment_variables.rst | 132 ++++++++++++++++++++++++ Documentation/index.rst | 1 + Documentation/meson.build | 1 + 3 files changed, 134 insertions(+) create mode 100644 Documentation/environment_variables.rst diff --git a/Documentation/environment_variables.rst b/Documentation/environment_variables.rst new file mode 100644 index 0000000..85346af --- /dev/null +++ b/Documentation/environment_variables.rst @@ -0,0 +1,132 @@ +Environment variables +===================== + +List of variables +----------------- + +LIBCAMERA_LOG_FILE + The custom destination for log output. + + Example value: ``/home/{user}/camera_log.log`` + +LIBCAMERA_LOG_LEVELS + Configure the verbosity of log messages for different categories (`more <#log-levels>`__) + + Example value: ``*:DEBUG`` + +LIBCAMERA_IPA_CONFIG_PATH + Define custom search locations for IPA configurations (`more <#ipa-configuration>`__) + + Example value: ``/usr/path/one:/tmp/path/two`` + +LIBCAMERA_IPA_MODULE_PATH + Define custom search locations for IPA modules (`more <#ipa-module>`__) + + Example value: ``/usr/path/one:/tmp/path/two`` + +Further details +--------------- + +Notes about debugging +~~~~~~~~~~~~~~~~~~~~~ + +The environment variables `LIBCAMERA_LOG_FILE` and `LIBCAMERA_LOG_LEVELS` +are used to modify the destination and verbosity of messages provided by +libcamera. + +The `LIBCAMERA_LOG_LEVELS` variable accepts a comma-separated list of +'category:level' pairs. + +The `level <#log-levels>`__ part is mandatory and can either be +specified by name or by numerical index associated with each level. + +The optional `category <#log-categories>`__ part is a regular +expression, which is matched against the categories defined by each +file in the source base using the logging infrastructure. + +For more information refer to the `API-documentation `__ + +Examples: + +Enable full debug output to a separate file, for every `category <#log-categories>`__ +within a local environment: + +.. code:: bash + + :~$ LIBCAMERA_LOG_FILE='/tmp/example_log.log' \ + LIBCAMERA_LOG_LEVELS=0 \ + cam --list + +Enable full debug output for the categories Camera & V4L2 within a +global environment: + +.. code:: bash + + :~$ export LIBCAMERA_LOG_LEVELS='Camera:DEBUG,V4L2:DEBUG' + :~$ cam --list + +Log levels +~~~~~~~~~~~ + +This is the list of available log levels, notice that all levels below +the chosen one are printed, while those above are discarded. + +- DEBUG (0) +- INFO (1) +- WARN (2) +- ERROR (3) +- FATAL (4) + +Example: +If you choose WARN (2), you will be able to see WARN (2), ERROR (3) & FATAL (4) +but not DEBUG (0) & INFO (1). + +Log categories +~~~~~~~~~~~~~~~ + +Every category represents a specific area of the libcamera codebase, +the names can be located within the source code, for example: +`src/libcamera/camera_manager.cpp `__ + +.. code:: bash + + LOG_DEFINE_CATEGORY(Camera) + +There are 2 available macros used to assign a category name to a part of the +libcamera codebase: + +LOG_DEFINE_CATEGORY + This macro is required, in order to use the `LOGC` macro for a + particular category. It can only be used once for each category. + If you want to create log messages within multiple compilation + units for the same category utilize the `LOG_DECLARE_CATEGORY` macro, + in every file except the definition file. +LOG_DECLARE_CATEGORY + Used for sharing an already defined category in between multiple + separate compilation units. + +Both macros have to be used within the libcamera namespace of the C++ source +code. + +IPA configuration +~~~~~~~~~~~~~~~~~~ + +The format and contents of the configuration file are specific to the +IPA (Image Processing Algorithm). It usually contains tuning parameters +for the IPA algorithms stored in JSON format. +The `LIBCAMERA_IPA_CONFIG_PATH` variable can be used to specify custom +storage locations to search for those configuration files. + +`Examples `__ + +IPA module +~~~~~~~~~~~ + +In order to locate the correct IPA module for your hardware, libcamera gathers +existing IPA modules from multiple locations. The default locations for this +operation are the installed system path (for example on Debian: +``/usr/local/x86_64-pc-linux-gnu/libcamera``) and the build directory. +With the `LIBCAMERA_IPA_MODULE_PATH`, you can specify a non-default +location to search for IPA modules. + +`Examples for existing IPA modules `__ diff --git a/Documentation/index.rst b/Documentation/index.rst index ff697d4..c49db18 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -17,3 +17,4 @@ Application Writer's Guide Pipeline Handler Writer's Guide Tracing guide + Environment variables diff --git a/Documentation/meson.build b/Documentation/meson.build index 26a12fc..8086abf 100644 --- a/Documentation/meson.build +++ b/Documentation/meson.build @@ -53,6 +53,7 @@ if sphinx.found() 'contributing.rst', 'docs.rst', 'index.rst', + 'environment_variables.rst', 'guides/introduction.rst', 'guides/application-developer.rst', 'guides/pipeline-handler.rst',