pcm.4: Remove DIAGNOSTICS section

These diagnostics do not exist anymore.

MFC after:	1 week

share/man/man4/pcm.4

@@ -23,7 +23,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd June 20, 2026
+.Dd October 7, 2026
 .Dt SOUND 4
 .Os
 .Sh NAME
@@ -646,14 +646,6 @@ This is handy if there are multiple
 devices available:
 .Pp
 .Dl mixer -d pcm1
-.Sh DIAGNOSTICS
-.Bl -diag
-.It pcm%d:play:%d:dsp%d.p%d: play interrupt timeout, channel dead
-The hardware does not generate interrupts to serve incoming (play)
-or outgoing (record) data.
-.It unsupported subdevice XX
-A device node is not created properly.
-.El
 .Sh SEE ALSO
 .Xr devfs 4 ,
 .Xr snd_ai2s 4 ,

sys/dev/sound/pcm/channel.c

@@ -477,7 +477,7 @@ chn_write(struct pcm_channel *c, struct uio *buf)
 			 *
 			 * 	 The idea is that, while set with CHN_F_NOTRIGGER,
 			 * 	 a channel isn't playing, *but* without this we
-			 * 	 end up with "interrupt timeout / channel dead".
+			 * 	 end up with interrupt timeout.
 			 */
 			ret = EAGAIN;
 		} else {