307013-003 Datasheet, PDF (738/848 Pages) Intel Corporation – Intel I/O Controller Hub 7

Intel® High Definition Audio Controller Registers (D27:F0)
19.2.12 INSTRMPAY—Input Stream Payload Capability
(Intel^® High Definition Audio Controller—D27:F0)
Memory Address:HDBAR + 1Ah
Default Value: 0018h
Attribute:
Size:
RO
16 bits
Bit
Description
15:14
Input FIFO Padding Type (IPADTYPE) — RO. This field indicates how the controller
pads the samples in the controller's buffer (FIFO). Controllers may not pad at all or may
pad to byte or memory container sizes.
0h = Controller pads all samples to bytes
1h = Reserved
2h = Controller pads to memory container size
3h = Controller does not pad and uses samples directly
13:0
Input Stream Payload Capability (INSTRMPAY) — RO. This field indicates the
maximum number of Words per frame for any single input stream. This measurement is
in 16-bit Word quantities per
48-kHz frame. The maximum supported is 24 Words (48B); therefore, a value of 18h is
reported in this register.
The value does not specify the number of words actually transmitted in the frame, but
is the size of the data as it will be placed into the controller's buffer (FIFO). Thus,
samples will be padded according to IPADTYPE before being stored into controller
buffer. To compute the supported streams, each sample is padded according to
IPADTYPE and then multiplied by the number of channels and samples per frame. If this
computed value is larger than INSTRMPAY, then that stream is not supported. As the
inbound stream tag is not stored with the samples it is not included in the word count.
The value may be larger than INPAY register value in some cases, although values less
than INPAY may also be invalid due to overhead. Software must ensure that a format
that would cause more Words per frame than indicated is not programmed into the
Input Stream Descriptor Register.
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Intel ^® ICH7 Family Datasheet