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Revision 7873bfb8

ID7873bfb866c89f9e6eab28b14d0c2007b361150c

Added by Hans de Goede almost 12 years ago

hw/ac97: Mask out unused bits of volume controls

The Linux ac97 drivers does a number of register read/write tests to
see how much resolution a volume control actually has.

This patch takes this into account by masking out any bits written to
a volume control reg which should not be there according to the spec.

After this the Linux ac97 driver correctly uses a range of 0 - 0x1f for
the PCM out volume, as stated in the spec, and we can fix the FIXME
in update_combined_volume_out().

This patch was also tested with a Windows XP guest without any issues.

Signed-off-by: Hans de Goede <>
Signed-off-by: malc <>

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