[PATCH 1/3] log: Allow LOG_DEBUG to always enable log output

[Simon Glass]

At present if CONFIG_LOG enabled, putting LOG_DEBUG at the top of a file
(before log.h inclusion) causes _log() to be executed for every log()
call, regardless of the build- or run-time logging level.

However there is no guarantee that the log record will actually be
displayed. If the current log level is lower than LOGL_DEBUG then it will
not be.

Add a way to signal that the log record should always be displayed and
update log_passes_filters() to handle this.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 common/log.c   |  6 +++++-
 doc/README.log |  7 ++-----
 include/log.h  | 16 ++++++++++++----
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/common/log.c b/common/log.c
index c5b9b489ca..db7bb7d145 100644
--- a/common/log.c
+++ b/common/log.c
@@ -153,6 +153,9 @@ static bool log_passes_filters(struct log_device *ldev, struct log_rec *rec)
 {
 	struct log_filter *filt;
 
+	if (rec->force_debug)
+		return true;
+
 	/* If there are no filters, filter on the default log level */
 	if (list_empty(&ldev->filter_head)) {
 		if (rec->level > gd->default_log_level)
@@ -204,7 +207,8 @@ int _log(enum log_category_t cat, enum log_level_t level, const char *file,
 	va_list args;
 
 	rec.cat = cat;
-	rec.level = level;
+	rec.level = level & LOGL_LEVEL_MASK;
+	rec.force_debug = level & LOGL_FORCE_DEBUG;
 	rec.file = file;
 	rec.line = line;
 	rec.func = func;
diff --git a/doc/README.log b/doc/README.log
index 1057981f45..0df0336fb3 100644
--- a/doc/README.log
+++ b/doc/README.log
@@ -77,11 +77,8 @@ Sometimes it is useful to turn on logging just in one file. You can use this:
    #define LOG_DEBUG
 
 to enable building in of all logging statements in a single file. Put it at
-the top of the file, before any #includes.
-
-To actually get U-Boot to output this you need to also set the default logging
-level - e.g. set CONFIG_LOG_DEFAULT_LEVEL to 7 (LOGL_DEBUG) or more. Otherwise
-debug output is suppressed and will not be generated.
+the top of the file, before any #includes. This overrides any log-level setting
+in U-Boot, including CONFIG_LOG_DEFAULT_LEVEL, but just for that file.
 
 
 Convenience functions
diff --git a/include/log.h b/include/log.h
index cf32351134..2e6e06cae6 100644
--- a/include/log.h
+++ b/include/log.h
@@ -29,6 +29,9 @@ enum log_level_t {
 	LOGL_COUNT,
 	LOGL_NONE,
 
+	LOGL_LEVEL_MASK = 0xf,	/* Mask for valid log levels */
+	LOGL_FORCE_DEBUG = 0x10, /* Mask to force output due to LOG_DEBUG */
+
 	LOGL_FIRST = LOGL_EMERG,
 	LOGL_MAX = LOGL_DEBUG_IO,
 };
@@ -129,7 +132,7 @@ static inline int _log_nop(enum log_category_t cat, enum log_level_t level,
 
 #if CONFIG_IS_ENABLED(LOG)
 #ifdef LOG_DEBUG
-#define _LOG_DEBUG	1
+#define _LOG_DEBUG	LOGL_FORCE_DEBUG
 #else
 #define _LOG_DEBUG	0
 #endif
@@ -137,9 +140,9 @@ static inline int _log_nop(enum log_category_t cat, enum log_level_t level,
 /* Emit a log record if the level is less that the maximum */
 #define log(_cat, _level, _fmt, _args...) ({ \
 	int _l = _level; \
-	if (CONFIG_IS_ENABLED(LOG) && (_l <= _LOG_MAX_LEVEL || _LOG_DEBUG)) \
-		_log((enum log_category_t)(_cat), _l, __FILE__, __LINE__, \
-		      __func__, \
+	if (CONFIG_IS_ENABLED(LOG) && (_LOG_DEBUG || _l <= _LOG_MAX_LEVEL)) \
+		_log((enum log_category_t)(_cat), _l | _LOG_DEBUG, __FILE__, \
+		     __LINE__, __func__, \
 		      pr_fmt(_fmt), ##_args); \
 	})
 #else
@@ -275,8 +278,12 @@ void __assert_fail(const char *assertion, const char *file, unsigned int line,
  * Memebers marked as 'allocated' are allocated (e.g. via strdup()) by the log
  * system.
  *
+ * TODO(sjg at chromium.org): Compress this struct down a bit to reduce space, e.g.
+ * a single u32 for cat, level, line and force_debug
+ *
  * @cat: Category, representing a uclass or part of U-Boot
  * @level: Severity level, less severe is higher
+ * @force_debug: Force output of debug
  * @file: Name of file where the log record was generated (not allocated)
  * @line: Line number where the log record was generated
  * @func: Function where the log record was generated (not allocated)
@@ -285,6 +292,7 @@ void __assert_fail(const char *assertion, const char *file, unsigned int line,
 struct log_rec {
 	enum log_category_t cat;
 	enum log_level_t level;
+	bool force_debug;
 	const char *file;
 	int line;
 	const char *func;
-- 
2.26.2.645.ge9eca65c58-goog