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AMD Geode™ LX Processors Data Book 323
Display Controller Register Descriptions
33234H
6.6.4.4 DC Video Y Buffer Start Address Offset (DC_VID_Y_ST_OFFSET)
This register specifies the offset at which the video Y (YUV 4:2:0) or YUV (YUV 4:2:2) buffer starts.
The upper 4 bits of this register are for the field count mechanism. This mechanism, which did not exist on previous
AMD Geode processors, allows the DC to fetch multiple fields or frames of VIP data without requiring software intervention
to move the offset. This mechanism has the constraint that the buffers for multiple video frames must be contiguous in
memory. (The VIP hardware will meet this constraint.)
Settings written to this register do not take effect until the start of the following frame or interlaced field.
6.6.4.5 DC Video U Buffer Start Address Offset (DC_VID_U_ST_OFFSET)
This register specifies the offset at which the video U (YUV 4:2:0) buffer starts.
Settings written to this register do not take effect until the start of the following frame or interlaced field.
DC Memory Offset 020h
Typ e R /W
Reset Value xxxxxxxxh
DC_VID_Y_ST_OFFSET Register Map
313029282726252423222120191817161514131211109876543210
RSVD OFFSET 0h
DC_VID_Y_ST_OFFSET Bit Descriptions
Bit Name Description
31:28 RSVD Reserved. Reserved for field count mechanism
27:0 OFFSET Video Y Buffer Start Offset. This value represents the starting location for Video Y
Buffer. The lower five bits should always be programmed as zero so that the start offset
is aligned to a 32-byte boundary. If YUV 4:2:2 mode is selected (DC Memory Offset
004h[20] = 0), the Video Y Buffer is used as a singular buffer holding interleaved Y, U and
V data. If YUV 4:2:0 is selected (DC Memory Offset 004h[20] = 1), the Video Y Buffer is
used to hold only Y data while U and V data are stored in separate buffers whose start
offsets are represented in DC_VID_U_ST_OFFSET (DC Memory Offset 024h[27:0]) and
DC_VID_V_ST_OFFSET (DC Memory Offset 028h[27:0]).
DC Memory Offset 024h
Typ e R /W
Reset Value xxxxxxxxh
DC_VID_U_ST_OFFSET Register Map
313029282726252423222120191817161514131211109876543210
FRAME_COUNT OFFSET 0