ICH4 gaps in sound.

[Pete Carah]

Mine is ICH3 with the same problem; this depends on a change sometime
between last Friday (worked fine) and this morning (broke) PST...

It looks as if someone made a change to interrupt routing sometime since 
the changes to the fsstat struct (I had recompiled then and the sound 
problem was NOT present; today I recompile and it is.)

I may be blowing smoke; the problem could also be in the sound driver
itself...

My system is a Sony VAIO R505ES with Yamaha sound chip, I suspect it
doesn't matter just which sound chip you have.

As I say, my sound was normal this morning with a compile on the 14th,
and is now broken.

There could also be a problem with interrupt sharing (almost everything
on this laptop is on IRQ 9), but enough other things work that I somehow
doubt it.  (first thing that normally breaks with interrupt sharing 
problems is my wi0 Orinoco built-in, and *that* is working fine.)

Problem here is that ICHx sound appears to depend on what some would
consider a redundant interrupt routing request (at least in VAIO 
configuration); several people in the past have "cleaned up" the apparent 
redundancy and it breaks Sony's sound :-(

dmesg excerpt here:
pcm0: <Intel ICH3 (82801CA)> port 0x18c0-0x18ff,0x1c00-0x1cff irq 9 at device 31.5 on pci0
pcm0: <Yamaha YMF753 AC97 Codec>

-- Pete