1 files changed, 38 insertions, 24 deletions

diff --git a/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl b/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
index 56723b42813e..87a7c07ab658 100644
--- a/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
+++ b/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
@@ -6134,44 +6134,58 @@ struct _snd_pcm_runtime {
       </para>
     </section>
 
-    <section id="useful-functions-snd-assert">
-      <title><function>snd_assert()</function></title>
+    <section id="useful-functions-snd-bug">
+      <title><function>snd_BUG()</function></title>
       <para>
-        <function>snd_assert()</function> macro is similar with the
-      normal <function>assert()</function> macro. For example,  
+        It shows the <computeroutput>BUG?</computeroutput> message and
+      stack trace as well as <function>snd_BUG_ON</function> at the point.
+      It's useful to show that a fatal error happens there. 
+      </para>
+      <para>
+         When no debug flag is set, this macro is ignored. 
+      </para>
+    </section>
+
+    <section id="useful-functions-snd-bug-on">
+      <title><function>snd_BUG_ON()</function></title>
+      <para>
+        <function>snd_BUG_ON()</function> macro is similar with
+        <function>WARN_ON()</function> macro. For example,  
 
         <informalexample>
           <programlisting>
 <![CDATA[
-  snd_assert(pointer != NULL, return -EINVAL);
+  snd_BUG_ON(!pointer);
 ]]>
           </programlisting>
         </informalexample>
-      </para>
 
-      <para>
-        The first argument is the expression to evaluate, and the
-      second argument is the action if it fails. When
-      <constant>CONFIG_SND_DEBUG</constant>, is set, it will show an
-      error message such as <computeroutput>BUG? (xxx)</computeroutput>
-      together with stack trace.
-      </para>
-      <para>
-         When no debug flag is set, this macro is ignored. 
-      </para>
-    </section>
+        or it can be used as the condition,
+        <informalexample>
+          <programlisting>
+<![CDATA[
+  if (snd_BUG_ON(non_zero_is_bug))
+          return -EINVAL;
+]]>
+          </programlisting>
+        </informalexample>
 
-    <section id="useful-functions-snd-bug">
-      <title><function>snd_BUG()</function></title>
-      <para>
-        It shows the <computeroutput>BUG?</computeroutput> message and
-      stack trace as well as <function>snd_assert</function> at the point.
-      It's useful to show that a fatal error happens there. 
       </para>
+
       <para>
-         When no debug flag is set, this macro is ignored. 
+        The macro takes an conditional expression to evaluate.
+        When <constant>CONFIG_SND_DEBUG</constant>, is set, the
+        expression is actually evaluated. If it's non-zero, it shows
+        the warning message such as
+        <computeroutput>BUG? (xxx)</computeroutput>
+        normally followed by stack trace.  It returns the evaluated
+        value.
+        When no <constant>CONFIG_SND_DEBUG</constant> is set, this
+        macro always returns zero.
       </para>
+
     </section>
+
   </chapter>