svn commit: r280682 - stable/9/share/man/man4

[Hans Petter Selasky]

Author: hselasky
Date: Thu Mar 26 10:26:25 2015
New Revision: 280682
URL: https://svnweb.freebsd.org/changeset/base/280682

Log:
  MFC r280262 and r280263:
  Add more known bugs to the USB audio manual page.

Modified:
  stable/9/share/man/man4/snd_uaudio.4
Directory Properties:
  stable/9/share/   (props changed)
  stable/9/share/man/   (props changed)
  stable/9/share/man/man4/   (props changed)

Modified: stable/9/share/man/man4/snd_uaudio.4
==============================================================================
--- stable/9/share/man/man4/snd_uaudio.4	Thu Mar 26 10:25:15 2015	(r280681)
+++ stable/9/share/man/man4/snd_uaudio.4	Thu Mar 26 10:26:25 2015	(r280682)
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 24, 2011
+.Dd March 19, 2015
 .Dt SND_UAUDIO 4
 .Os
 .Sh NAME
@@ -91,12 +91,27 @@ by
 The
 .Tn PCM
 framework in
-.Fx ,
-as of this writing, does not handle device un-registrations in a properly
-abstracted manner, i.e., a detach request is refused by the
-.Tn PCM
-framework if the device is in use.
-It is necessary to allow the device un-registration to complete
-successfully, otherwise the
+.Fx
+only supports synchronous device detach.
+That means all mixer and DSP character devices belonging to a given
+USB audio device must be closed when receiving an error on a DSP read,
+a DSP write or a DSP IOCTL request.
+Else the USB audio driver will wait for this to happen, preventing
+enumeration of new devices on the parenting USB controller.
+.Pp
+Some USB audio devices might refuse to work properly unless the sample
+rate is configured the same for both recording and playback, even if
+only simplex is used.
+See the
+.Va dev.pcm.%d.[play|rec].vchanrate
+sysctls.
+.Pp
+The
 .Tn PCM
-layer will panic.
+framework in
+.Fx
+currently doesn't support the full set of USB audio mixer
+controls.
+Some mixer controls are only available as
+.Va dev.pcm.%d.mixer
+sysctls.