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5-146 C141-E203-01EN
5.4.4 DMA data-in command protocol
DMA data-in commands include the following commands:
• READ DMA (EXT)
• IDENTFY DMA
The DMA mechanism transfers data of more than one block from the device to the
host. The completion of a command is reported by an interruption.
An outline of this protocol is as follows:
1) The device receives a DMA data-in command with the Register HD FIS.
2) If an error remaining in the device prevents command execution, the device
sends the Register DH FIS with 1 set in the I bit.
3) When the device is ready to send data, it sends the Data FIS to the host.
4) When all data has been transferred, the device sends the Register DH FIS
(with 1 set in the I bit) to complete execution of the command. If any data
remains to be sent by the device, this protocol is repeated starting from step 3).
(The maximum data size is 8 KB.)
Device
Host
RegHD
DATA
RegDH
Figure 5.13 DMA data-in command protocol