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12.20 Read FPDMA Queued (60h)
The Read FPDMA command reads one or more sectors of data from disk media, and then transfers the data from
the device to the host.
If an uncorrectable error occurs, the read will be terminated at the failing sector.
Table 120 Read FPDMA Queued Command (60h)
Command Input
Field
Description
FEATURE
The number of logical sectors to be transferred. A value of 0000h
indicates that 65536 logical sectors are to be transferred
COUNT
Bit
Description
15:14
PRIO field
13:8
Reserved
7:3
NCQ TAG field
2:0
Reserved
LBA
LBA of first logical sector to be transferred
ICC
7:0 ICC field
DEVICE
Bit Description
7 FUA bit
6 Shall be set to one
5 Reserved
4 Shall be cleared to zero
3:0 Reserved
Command
7:0 60h
PRIO field
The Priority (PRIO) value shall be assigned by the host based on the priority of the command issued. The device
makes a best effort to complete High priority requests in a more timely fashion than Normal and isochronous priority
requests. The device tries to complete isochronous requests prior to its associated deadline. The Priority values are
defined as follows:
00b Normal priority
01b Isochronous – deadline dependent priority
10b High priority
NCQ TAG field
The TAG value shall be assigned to be different from all other queued commands. The value shall not exceed the
maximum queue depth specified by the Word 75 of the Identify Device information.
FUA bit
When the FUA bit is set to 1, the requested data is always retrieved from the media regardless of whether the data
are held in the sector buffer or not.
When the FUA bit is set to 0, the data may be retrieved from the media or from the cached data left by previously
processed Read or Write commands.
ICC field
The Isochronous Command Completion (ICC) field is valid when PRIO is set to a value of 01b. It is assigned by the
host based on the intended deadline associated with the command issued. When a deadline has expired, the device
continues to complete the command as soon as possible. The host can modify this behavior if the device supports
the NCQ Non-Data command (see Section 12.15) and supports the Deadline Handling subcommand (see Section
12.15.2). This subcommand allows the host to set whether the device aborts commands that have exceeded the time
set in ICC.
There are several parameters encoded in the ICC field: Fine or Coarse timing, Interval, and the Max Time. The
Interval indicates the time units of the Time Limit parameter.
If ICC Bit 7 cleared to zero, then the time interval is fine-grained.
Interval = 10msec
Time Limit = (ICC[6:0] + 1) * 10 msec
190
Hard Disk Drive Specification