ALSA: Add debug module option

Add debug module option to snd core.
This controls the debug print level.  When CONFIG_SND_DEBUG_VERBOSE
is set, you can suppress the debug messages by giving or changing this
parameter to a lower value.  debug=0 means no debug messsages.
As default, it's set to the verbose level 2.

Since this option can be changed dynamically via sysfs file, you can
suppress the verbose debug messages on the fly, which wasn't possible
before.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 39 insertions, 28 deletions

diff --git a/sound/core/misc.c b/sound/core/misc.c
index 1d29e678369e..23a032c6d487 100644
--- a/sound/core/misc.c
+++ b/sound/core/misc.c
@@ -24,6 +24,20 @@
 #include <linux/ioport.h>
 #include <sound/core.h>
 
+#ifdef CONFIG_SND_DEBUG
+
+#ifdef CONFIG_SND_DEBUG_VERBOSE
+#define DEFAULT_DEBUG_LEVEL     2
+#else
+#define DEFAULT_DEBUG_LEVEL     1
+#endif
+
+static int debug = DEFAULT_DEBUG_LEVEL;
+module_param(debug, int, 0644);
+MODULE_PARM_DESC(debug, "Debug level (0 = disable)");
+
+#endif /* CONFIG_SND_DEBUG */
+
 void release_and_free_resource(struct resource *res)
 {
         if (res) {
@@ -35,6 +49,7 @@ void release_and_free_resource(struct resource *res)
 EXPORT_SYMBOL(release_and_free_resource);
 
 #ifdef CONFIG_SND_VERBOSE_PRINTK
+/* strip the leading path if the given path is absolute */
 static const char *sanity_file_name(const char *path)
 {
         if (*path == '/')
@@ -43,48 +58,44 @@ static const char *sanity_file_name(const char *path)
                 return path;
 }
 
-void snd_verbose_printk(const char *path, int line, const char *format, ...)
+/* print file and line with a certain printk prefix */
+static int print_snd_pfx(unsigned int level, const char *path, int line,
+                         const char *format)
 {
         const char *file = sanity_file_name(path);
-        va_list args;
-        
-        if (format[0] == '<' && format[1] >= '0' && format[1] <= '7' && format[2] == '>') {
-                char tmp[] = "<0>";
+        char tmp[] = "<0>";
+        const char *pfx = level ? KERN_DEBUG : KERN_DEFAULT;
+        int ret = 0;
+
+        if (format[0] == '<' && format[2] == '>') {
                 tmp[1] = format[1];
-                printk("%sALSA %s:%d: ", tmp, file, line);
-                format += 3;
-        } else {
-                printk("ALSA %s:%d: ", file, line);
+                pfx = tmp;
+                ret = 1;
         }
-        va_start(args, format);
-        vprintk(format, args);
-        va_end(args);
+        printk("%sALSA %s:%d: ", pfx, file, line);
+        return ret;
 }
-
-EXPORT_SYMBOL(snd_verbose_printk);
+#else
+#define print_snd_pfx(level, path, line, format)        0
 #endif
 
-#if defined(CONFIG_SND_DEBUG) && defined(CONFIG_SND_VERBOSE_PRINTK)
-void snd_verbose_printd(const char *path, int line, const char *format, ...)
+#if defined(CONFIG_SND_DEBUG) || defined(CONFIG_SND_VERBOSE_PRINTK)
+void __snd_printk(unsigned int level, const char *path, int line,
+                  const char *format, ...)
 {
-        const char *file = sanity_file_name(path);
         va_list args;
         
-        if (format[0] == '<' && format[1] >= '0' && format[1] <= '7' && format[2] == '>') {
-                char tmp[] = "<0>";
-                tmp[1] = format[1];
-                printk("%sALSA %s:%d: ", tmp, file, line);
-                format += 3;
-        } else {
-                printk(KERN_DEBUG "ALSA %s:%d: ", file, line);
-        }
+#ifdef CONFIG_SND_DEBUG 
+        if (debug < level)
+                return;
+#endif
         va_start(args, format);
+        if (print_snd_pfx(level, path, line, format))
+                format += 3; /* skip the printk level-prefix */
         vprintk(format, args);
         va_end(args);
-
 }
-
-EXPORT_SYMBOL(snd_verbose_printd);
+EXPORT_SYMBOL_GPL(__snd_printk);
 #endif
 
 #ifdef CONFIG_PCI