Table of Contents
Advertisement
Theory of Operation
R
Figure 9. Power-on to Device Ready Elapsed Time
Device
Ready
BSY == 0
Power
System SW
SATA HW
DRDY == 1
On
sets PxE
sets PxP
Time
x
0
ms,
y
z
us or
ms
ms or secs
secs
In Figure 9, the total elapsed time from power on until a device attached to a SATA port is
"ready." is the sum of the amount of elapsed time shown above (x + y + z). In the figure above, the
time value 'x' is the amount of time that elapses prior to the setting of the PxE bit by system
software. This value may measure in microseconds, milliseconds or seconds – its value is
dependent on when system software sets the PxE bit.
The time value 'y' can be up to 10ms plus an unspecified amount of time (as per the Serial ATA:
High Speed Serialized AT Attachment v1.0 specification - this document is available from the
Serial ATA Working Group at: http://www.serialata.org/). This duration is highly dependent on
the manufacturer of the SATA device.
The time value 'z' is bound to an upper value and is defined by the AT Attachment with Packet
Interface – 6 (ATA/ATAPI-6) Specification, available from the T13 Technical Committee at:
http://www.t13.org/.
If the PxP bit is not set by the ICH5 SATA PHY at some interval within the time denoted by x + y
+ z, then system software shall assume that no device is present on the port.
As noted in the figure above, the PxP bits only indicate device presence; device readiness (e.g.,
able to receive commands) shall be determined by an examination of the Status register (contained
within the appropriate channel control register). The device indicates 'readiness' when the device
is 1) Not busy (BSY == 0) and 2) is ready (DRDY == 1). This is identical to how device
presence/readiness is determined for P-ATA devices.
SATA Programmer's Reference Manual
27
Advertisement
Table of Contents
