[haiku-bugs] Re: [Haiku] #4755: ICH7, 8 & 9 Audio Not working with Alpha

  • From: "kvdman" <trac@xxxxxxxxxxxx>
  • Date: Thu, 08 Apr 2010 16:35:59 -0000

#4755: ICH7, 8 & 9 Audio Not working with Alpha
-------------------------------+--------------------------------------------
 Reporter:  kvdman             |       Owner:  korli    
     Type:  bug                |      Status:  new      
 Priority:  normal             |   Milestone:  R1       
Component:  Drivers/Audio/HDA  |     Version:  R1/alpha1
 Keywords:                     |   Blockedby:           
 Platform:  All                |    Blocking:           
-------------------------------+--------------------------------------------

Comment(by kvdman):

 Hello,

 I thought this info may be useful? Perhaps you already know this:

 http://www.haiku-os.org/community/forum/hardware_compatibility_wiki

 The situation with Intel HDA is that it's a class standard, like VGA or
 USB storage.

 So in theory you write one driver which implements the software side of
 the standard according to the documentation, and all conforming hardware
 will work. The Haiku driver roughly follows this approach, its probe
 function matches any PCI device which has the class information indicating
 it implements Intel HDA. Thus probably anyone with a modern Intel HDA
 device (which is most new laptops and desktops) gets this driver selected.

 However, the HDA specification itself represents the codec (the bit that
 actually converts between PCM data and any form of sound output or input
 connector) as a separately programmed component. It is often the case that
 additional code is needed for a particular vendor's codec, or for some
 applications (ie specific models of computer or sound cards) of that
 codec. The Haiku code includes some examples of such additional code,
 covering some very popular devices, but it looks rather less than
 comprehensive. So for some users the outcome is likely that Haiku's driver
 seems to work, except that no sound comes out (it is playing, but to some
 unconnected pins deep inside their laptop, not to the speakers), or the
 volume controls don't work, or the speakers on their laptop always play
 sound even with headphones plugged in, that sort of thing.

 The codecs have unique hardware identifiers similar to PCI devices, so
 that the OS need only load driver software for the codecs used in the
 installed device. e.g. ALSA identifies the codec in this laptop and loads
 a driver for 'snd-hda-codec-id:14f15051' a Conexant chip. So if Haiku
 actually had the new Windows 95 style driver model, this information could
 have been gathered too. But it might not be that helpful, at a certain
 point you do have to rely on user feedback on whether it really works. The
 same Conexant chip that works fine in this laptop might be wired up
 differently in another model, leaving the microphone non-functional by
 default.

-- 
Ticket URL: <http://dev.haiku-os.org/ticket/4755#comment:19>
Haiku <http://dev.haiku-os.org>
Haiku - the operating system.

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