Samsung S3C6400X, User Manual, Page: 906 / 1189

PRELIMINARY
HSMMC CONTROLLER S3C6400X RISC MICROPROCESSOR
27-30
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
The Response Field indicates bit positions of “Responses” defined in the PHYSICAL LAYER SPECIFICATION
Version 1.01. The Table (upper) shows that most responses with a length of 48 (R[47:0]) have 32 bits of the
response data (R[39:8]) stored in the
Response register at REP[31:0]. Responses of type R1b (Auto CMD12
responses) have response data bits R[39:8] stored in the Response register at REP[127:96]. Responses with
length 136 (R[135:0]) have 120 bits of the response data (R[127:8]) stored in the Response register at
REP[119:0].
To be able to read the response status efficiently, the Host Controller only stores part of the response data in the
Response register. This enables the Host Driver to efficiently read 32 bits of response data in one read cycle on a
32-bit bus system. Parts of the response, the Index field and the CRC, are checked by the Host Controller (as
specified by the
Command Index Check Enable and the Command CRC Check Enable bits in the Command
register) and generate an error interrupt if an error is detected. The bit range for the CRC check depends on the
response length. If the response length is 48, the Host Controller shall check R[47:1], and if the response length is
136 the Host Controller shall check R[119:1].
Since the Host Controller may have a multiple block data DAT line transfer executing concurrently with a
CMD_wo_DAT command, the Host Controller stores the Auto CMD12 response in the upper bits (REP[127:96]) of
the
Response register. The CMD_wo_DAT response is stored in REP[31:0]. This allows the Host Controller to
avoid overwriting the Auto CMD12 response with the CMD_wo_DAT and vice versa.
When the Host Controller modifies part of the Response register, as shown in the Table above, it shall preserve
the unmodified bits.