2000-11-25 13:09:58

by Paul Warren

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Subject: Problem with NM256 and APM

I have a problem with APM interfering with sound playback through a
NeoMagic 256.

If I have sound playing, and do a "cat /proc/apm" I get a noticeable
glitch in sound playback. The glitch sounds like playback skips
backwards by a fraction of a second.

The machine is a Dell Latitude CS, and I have seen this problem on
2.2.17 and 2.4.0test11.

The anonymous author of the NM256 driver claims to have not seen this
problem before.

dmesg says:

apm: BIOS version 1.2 Flags 0x03 (Driver version 1.13)
NeoMagic 256AV/256ZX audio driver, version 1.1
NM256: Found card signature in video RAM: 0x3fec00
NM256: Mapping port 1 from 0x3e6c00 - 0x3fec00
Initialized NeoMagic 256ZX audio in PCI native mode
Initialized AC97 mixer
Done installing NM256 audio driver.

Any clues as to what might be behind this?