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@@ -96,16 +96,45 @@ Also debug() and error() will generate log records - these use LOG_CATEGORY
as the category, so you should #define this right at the top of the source
file to ensure the category is correct.
+Generally each log format_string ends with a newline. If it does not, then the
+next log statement will have the LOGRECF_CONT flag set. This can be used to
+continue the statement on the same line as the previous one without emitting
+new header information (such as category/level). This behaviour is implemented
+with log_console. Here is an example that prints a list all on one line with
+the tags at the start:
+
+.. code-block:: c
+
+ log_debug("Here is a list:");
+ for (i = 0; i < count; i++)
+ log_debug(" item %d", i);
+ log_debug("\n");
+
+Also see the special category LOGL_CONT and level LOGC_CONT.
+
You can also define CONFIG_LOG_ERROR_RETURN to enable the log_ret() macro. This
can be used whenever your function returns an error value:
.. code-block:: c
- return log_ret(uclass_first_device(UCLASS_MMC, &dev));
+ return log_ret(uclass_first_device_err(UCLASS_MMC, &dev));
This will write a log record when an error code is detected (a value < 0). This
can make it easier to trace errors that are generated deep in the call stack.
+The log_msg_ret() variant will print a short string if CONFIG_LOG_ERROR_RETURN
+is enabled. So long as the string is unique within the function you can normally
+determine exactly which call failed:
+
+.. code-block:: c
+
+ ret = gpio_request_by_name(dev, "cd-gpios", 0, &desc, GPIOD_IS_IN);
+ if (ret)
+ return log_msg_ret("gpio", ret);
+
+Some functions return 0 for success and any other value is an error. For these,
+log_retz() and log_msg_retz() are available.
+
Convenience functions
~~~~~~~~~~~~~~~~~~~~~