I was using the 2.6.7 kernel without APIC or ACPI support, and the via82xx
driver worked perfectly, compiled as a module, without any options. I built a
new 2.6.7 kernel on the same hardware with APIC and ACPI support in the
kernel, as the board supports it, and the driver did not work correctly. When
sound was played, a short, 1 second long bit of the sound to be played was
looped. Possibly this is the clicking noise described by some people? The
driver works fine with this new kernel after adding the option
"dxs_support=1". I hope this interaction with ACPI and APIC sheds some light
on some of the troubles with this driver. I can provide more information if
anyone wants it. Please CC me, I'm not on the list.
TJ
Motherboard: MSI K7T266 Pro2
lspci -nv:
00:00.0 Class 0600: 1106:3099
Subsystem: 1106:0000
Flags: bus master, medium devsel, latency 0
Memory at e0000000 (32-bit, prefetchable) [size=64M]
Capabilities: [a0] AGP version 2.0
Capabilities: [c0] Power Management version 2
00:01.0 Class 0604: 1106:b099
Flags: bus master, 66Mhz, medium devsel, latency 0
Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
Memory behind bridge: dfc00000-dfcfffff
Prefetchable memory behind bridge: dfa00000-dfafffff
Capabilities: [80] Power Management version 2
00:06.0 Class 0200: 8086:100e (rev 02)
Subsystem: 8086:002e
Flags: bus master, 66Mhz, medium devsel, latency 96, IRQ 17
Memory at dffc0000 (32-bit, non-prefetchable) [size=128K]
Memory at dffa0000 (32-bit, non-prefetchable) [size=128K]
I/O ports at d800 [size=64]
Expansion ROM at dff80000 [disabled] [size=128K]
Capabilities: [dc] Power Management version 2
Capabilities: [e4] PCI-X non-bridge device.
Capabilities: [f0] Message Signalled Interrupts: 64bit+ Queue=0/0
Enable
-
00:07.0 Class 0200: 1317:0985 (rev 11)
Subsystem: 1317:0570
Flags: bus master, medium devsel, latency 96, IRQ 18
I/O ports at d400 [size=256]
Memory at dfffbc00 (32-bit, non-prefetchable) [size=1K]
Expansion ROM at dff60000 [disabled] [size=128K]
Capabilities: [c0] Power Management version 2
00:08.0 Class 0180: 105a:4d69 (rev 02) (prog-if 85)
Subsystem: 105a:4d68
Flags: bus master, 66Mhz, slow devsel, latency 96, IRQ 19
I/O ports at ec00 [size=8]
I/O ports at e800 [size=4]
I/O ports at e400 [size=8]
I/O ports at e000 [size=4]
I/O ports at dc00 [size=16]
Memory at dfffc000 (32-bit, non-prefetchable) [size=16K]
Expansion ROM at dffe0000 [disabled] [size=16K]
Capabilities: [60] Power Management version 1
00:09.0 Class 0180: 1095:0680 (rev 01)
Subsystem: 1095:0680
Flags: bus master, medium devsel, latency 96, IRQ 16
I/O ports at d000 [size=8]
I/O ports at cc00 [size=4]
I/O ports at c800 [size=8]
I/O ports at c400 [size=4]
I/O ports at c000 [size=16]
Memory at dfffbb00 (32-bit, non-prefetchable) [size=256]
Expansion ROM at dfe80000 [disabled] [size=512K]
Capabilities: [60] Power Management version 2
00:11.0 Class 0601: 1106:3074
Subsystem: 1106:0000
Flags: bus master, stepping, medium devsel, latency 0
Capabilities: [c0] Power Management version 2
00:11.1 Class 0101: 1106:0571 (rev 06) (prog-if 8a [Master SecP PriP])
Subsystem: 1106:0571
Flags: bus master, medium devsel, latency 32
I/O ports at fc00 [size=16]
Capabilities: [c0] Power Management version 2
00:11.5 Class 0401: 1106:3059 (rev 10)
Subsystem: 4005:4710
Flags: medium devsel, IRQ 28
I/O ports at bc00 [size=256]
Capabilities: [c0] Power Management version 2
-------------------------------------------------------
On Sun, 17 Apr 2005 12:53:24 -0400 TJ wrote:
> I was using the 2.6.7 kernel without APIC or ACPI support, and the via82xx
> driver worked perfectly, compiled as a module, without any options. I built a
> new 2.6.7 kernel on the same hardware with APIC and ACPI support in the
> kernel, as the board supports it, and the driver did not work correctly.
2.6.7 is pretty old; there were many bugfixes in both ACPI and sound
drivers since that time.
> When sound was played, a short, 1 second long bit of the sound to be
> played was looped. Possibly this is the clicking noise described by
> some people?
Does not look like it. The most common cause of looping sound are
interrupt problems, and unfortunately ACPI (especially when coupled
with APIC support) often triggers them (sometimes because of bugs in
the kernel ACPI support, sometimes because a buggy BIOS supplies
broken data).
If interrupts are not working, usually this happens:
- The driver sets up a circular buffer which contains the first
portion of sound samples to be played, and starts the playback
hardware.
- The sound card reads the samples from the buffer; when it reaches
some point in the buffer, it sends the interrupt signal, notifying
the driver about it.
- Normally, when the driver handles the interrupt, it will place more
sound data in the circular buffer (or, in the mmap mode, it will
notify the application, which will write to the buffer directly).
However, if interrupts are not working, the driver will never get
such notification, and the same portion of sound samples will stay
in the buffer forever. The sound card does not know that the buffer
was not updated and will play that piece of sound forever.
Another symptom of not working interrupts is that aplay just hangs
forever (aplay -vv should draw a histogram of played data).
> The driver works fine with this new kernel after adding the option
> "dxs_support=1".
This is very strange - the dxs_support option should not cause such
changes. Usually the problem caused by a wrong dxs_support value is
that sound is basically there, but distorted.
Also, seems that dxs_support=1 should not work at all (at least in
theory). dxs_support=4 seems to be more correct; latest code in ALSA
CVS supports dxs_support=5, which uses more capabilities of the
hardware (apparently the VIA VT8233/5/7 chips are able to perform
sample rate conversion from arbitrary rates to 48000 Hz with 4
independent channels).
> I hope this interaction with ACPI and APIC sheds some light on some
> of the troubles with this driver.
Most likely you have some trouble with ACPI (either with the buggy
implementation in 2.6.7, or with the buggy BIOS, or maybe both).
> I can provide more information if
> anyone wants it. Please CC me, I'm not on the list.
>
> TJ
>
> Motherboard: MSI K7T266 Pro2
>
> 00:11.5 Class 0401: 1106:3059 (rev 10)
Hmm, seems to be some old chip revision:
#define VIA_REV_PRE_8233 0x10 /* not in market */
> Subsystem: 4005:4710
Not in the known devices list of snd-via82xx (this list contains
working values of the dxs_support option for known boards). But you
should report it to ALSA developers (e.g., in their bug tracking
system, https://bugtrack.alsa-project.org/alsa-bug/ ) - your message
to LKML will likely be lost.
> Flags: medium devsel, IRQ 28
> I/O ports at bc00 [size=256]
> Capabilities: [c0] Power Management version 2