HEADS UP: snd_hda MFC plan

Alexander Motin mav at FreeBSD.org
Tue Jan 6 09:35:03 UTC 2009

Alexander Leidinger wrote:
> Quoting Alexander Motin <mav at FreeBSD.org> (from Tue, 06 Jan 2009
> 00:13:58 +0200):
>> On most systems having several devices is not a problem, as mostly
>> used analog connectors are usually detected first. But on some systems
>> (for example, having separate HDMI ports on video cards, which are now
>> also supported and often detected first), user may be required to
>> explicitly configure his audio applications or by using
>> hw.snd.default_unit sysctl globally specify default audio device he
>> wants to use. This moment explicitly specified in updated man page and
>> I am going to specify it in UPDATING.
> Is there a way to move those HDMI ports to the end (either in pcmX or in
> the probing) somehow? If yes, it would be more POLA to do this instead
> of requiring the users to do something.

HDMI ports usually have separate PCI HDA controllers. So order of pcm
devices there defined by PCI probe order. Two driver instances know
nothing about each other and I don't like the idea of obtaining such

> And related: do all detected analog ports appear in a sensible order?
> What I mean is again POLA related. If someone updates from 7.1 to 7.2,
> will he be required to do something to get sound out of the same
> connector as before when connecting to the default audio device? If not,
> is it possible for you to introduce some corresponding sorting before
> MFCing?

Order of ports withing one codec defined by hardware vendor via codec
configuration done by BIOS. That configuration supposed to be optimal
for the specific system. Taking that previous driver ignored most of
this information and was less functional, there sure will be some usage
differences, but most configurations I have seen are quite reasonable to
work just out of the box.

Alexander Motin

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