FW82801DBM S L6DN Intel, FW82801DBM S L6DN Datasheet - Page 256

• Manufacturer Part Number: FW82801DBM S L6DN
• Manufacturer: Intel

Specifications of FW82801DBM S L6DN

• Lead Free Status / RoHS Status: Not Compliant

Functional Description
5.19.7
5.19.8
256
Hardware Assist to Determine AC_SDIN Used Per Codec
Software first performs a read to one of the audio codecs. The read request goes out on
AC_SDOUT. Since under our micro-architecture only one read can be performed at a time on the
link, eventually the read data will come back in on one of the AC_SDIN[2:0] lines.
The codec will do this by indicating that status data is valid in its TAG, then echo the read address
in slot 1 followed by the read data in slot 2.
The new function of the ICH4 hardware is to notice which AC_SDIN line contains the read return
data, and to set new bits in the new register indicating which AC_SDIN line the register read data
returned on. If it returned on AC_SDIN0, bits [1:0] contain the value 00. If it returned on
AC_SDIN1, the bits contain the value 01, etc.
ICH4 hardware can set these bits every time register read data is returned from a function 5 read.
No special command is necessary to cause the bits to be set. The new driver/BIOS software will
read the bits from this register when it cares to, and can ignore it otherwise. When software is
attempting to establish the codec-to-AC_SDIN mapping, it will single feed the read request and not
pipeline to ensure it gets the right mapping, we cannot ensure the serialization of the access.
Software Mapping of AC_SDIN to DMA Engine
Once software has performed the register read to determine codec-to-AC_SDIN mapping, it will
then either set bits 5:4 or 7:6 in the SDATA_IN MAP register to map this codec to the DMA
engine. After it maps the audio codecs, it will set the “SE” (steer enable) bit, which now lets the
hardware know to no longer OR the AC_SDIN lines, and to use the mappings in the register to
steer the appropriate AC_SDIN line to the correct DMA engines.
Intel
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82801DBM ICH4-M Datasheet