307013-003 Datasheet, PDF (755/848 Pages) Intel Corporation – Intel I/O Controller Hub 7

Intel® High Definition Audio Controller Registers (D27:F0)
19.2.42 SDFIFOS—Stream Descriptor FIFO Size Register
(Intel^® High Definition Audio Controller—D27:F0)
Memory Address:Input Stream[0]: HDBAR + 90h
Input Stream[1]: HDBAR + B0h
Input Stream[2]: HDBAR + D0h
Input Stream[3]: HDBAR + F0h
Output Stream[0]: HDBAR + 110h
Output Stream[1]: HDBAR + 130h
Output Stream[2]: HDBAR + 150h
Output Stream[3]: HDBAR + 170h
Attribute: Input: RO
Output: R/W
Default Value:
Input Stream: 0077h
Output Stream: 00BFh
Size:
16 bits
Bit
Description
15:8
Reserved.
FIFO Size — RO (Input stream), R/W (Output stream). This field indicates the
maximum number of bytes that could be fetched by the controller at one time. This is
the maximum number of bytes that may have been DMA’d into memory but not yet
transmitted on the link, and is also the maximum possible value that the PICB count
will increase by at one time.
The value in this field is different for input and output streams. It is also dependent on
the Bits per Samples setting for the corresponding stream. Following are the values
read/written from/to this register for input and output streams, and for non-padded
and padded bit formats:
Output Stream R/W value:
Value
Output Streams
0Fh = 16B
8, 16, 20, 24, or 32 bit Output Streams
1Fh = 32B
8, 16, 20, 24, or 32 bit Output Streams
3Fh = 64B
8, 16, 20, 24, or 32 bit Output Streams
7Fh = 128B
8, 16, 20, 24, or 32 bit Output Streams
7:0
BFh = 192B
8, 16, or 32 bit Output Streams
FFh = 256B
20, 24 bit Output Streams
NOTES:
1.
All other values not listed are not supported.
2.
When the output stream is programmed to an unsupported size, the hardware
sets itself to the default value (BFh).
3.
Software must read the bit field to test if the value is supported after setting the
bit field.
Input Stream RO value:
Value
77h = 120B
9Fh = 160B
Input Streams
8, 16, 32 bit Input Streams
20, 24 bit Input Streams
NOTE: The default value is different for input and output streams, and reflects the
default state of the BITS fields (in Stream Descriptor Format registers) for the
corresponding stream.
Intel ^® ICH7 Family Datasheet
755