SATA Device Initiated Power Management (DIPM)

Add to my manuals
10 Pages

advertisement

SATA Device Initiated Power Management (DIPM) | Manualzz

John Masiewicz

ATA/ATAPI

T13 / e04149-r0

ATA Power Management

“SATA Device Initiated Power

Management (DIPM)”

John Masiewicz

Western Digital [email protected]

949-672-7686

October 8, 2004

Background

„

SATA Interface Power Management

†

Applies to SATA Phy block only

†

Independent of drive power management

†

Can be tied to drive PM: Standby, Sleep, Idle

†

SATA interface PM has three states

†

ACTIVE: Phy ready, full power, TX/RX on

†

PARTIAL: reduced power, resumes in under 10 us

†

SLUMBER: reduced power, resumes in under 10 ms e04149-r0

10-5-04

2

Background

Active

PARTIAL

X SLUMBER

10-5-04

†

Entering PARTIAL or SLUMBER

†

Host or device may send PMREQ_P or PMREQ_S

†

To resume from PARTIAL or SLUMBER, either host or device

†

†

Sends COMWAKE OOB, Receives COMWAKE response, and moves to Phy ready.

Resumes right where it left off

†

Main question is “WHEN” should a Device initiate SATA PM?

e04149-r0 3

Implementation

„

IDENTIFY DEVICE

†

Word 76, Bit 9

†

If 1, Device supports receipt of host initiated interface PM

†

Word 78, Bit 3

†

If 1, Device supports initiating interface PM

†

Word 79, Bit 3

†

If 1, Device initiating interface PM is enabled.

„

SET FEATURES command to enable/disable e04149-r0

10-5-04

4

Host Initiated Power Management

„

Host Initiated Interface PM (HIPM)

†

Device should be able to respond to PMREQ_P, PMREQ_S &

COMWAKE, and change Phy Power Management state.

†

Device should not NAK PM requests from host.

†

If host issues PMREQ while commands are queued, it is better to enter PM and then issue COMWAKE to host when a released command is ready for data transfer.

†

Exception, data is ready to transfer when PMREQ received, and device sends X_RDY (not NAK).

†

Very simple if no commands are outstanding.

†

Device will not exit PM, wait for Host COMWAKE e04149-r0

10-5-04

5

Device Initiated Power Management

„

Device Initiated Interface PM (DIPM)

†

If enabled, Device is manages SATA Interface power

†

Based on Command Status and Partial/Slumber timers

†

Programmable timers allow for more / less aggressive models.

†

Implement two timers:

†

Partial Timer (Typically 1-5 ms ?)

†

Slumber Timer (Typically 5-100 ms ?)

†

HW or FW timers, and same timer feature can be used for both.

†

May be host programmable, (SET FEATURES or VSC commands?)

†

An implementation algorithm is proposed here that implements DIPM without new commands or Serial Transport

Features.

e04149-r0

10-5-04

6

Device Initiated Interface PM

„

Recommended DIPM Algorithm

†

Following assumptions are made

†

Device must support SATA PM protocol. (PMREQ_P,

PMREQ_S)

†

Timer (HW/FW) be used for Partial/Slumber timers.

†

COMWAKE or Phy Ready interrupt to inform link of

Resume.

†

COMRESET detection still functional while in PM modes

†

Some start / Stop Device Initiated PM timer/function

†

Algorithm based e04149-r0

10-5-04

7

Device Initiated Interface PM

„

Recommended DIPM Algorithm, continue…

†

PARTIAL timer:

†

Clear/Stop Partial timer when a transfer starts, TX or RX.

†

Load/Start Partial timer when a transfer is complete, TX or RX.

†

When timer expires

†

Initiate PARTIAL state.

†

If PARTIAL successful, Load/Start SLUMBER timer.

†

SLUMBER timer:

†

When timer expires

†

Transmit COMWAKE to go to ACTIVE.

†

Initiate PMREQ_S to go to SLUMBER state.

†

If host NAK’s Slumber, restart PARTIAL timer.

e04149-r0

10-5-04

8

Device Initiated Interface PM

POWER

UP

Host o r Devic e COM

WAKE

Host or Device COMWAKE

SLUMBER

STATE

Drive PM

Sleep,

Standby,

Idle

Host P

MAC

K

Host PMNAK

ACTIVE1

Load/Start

PARTIAL

Timer

PARTIAL timer

Expired

X_RDY

ACTIVE3

Device Init

PARTIAL

Send

PMREQ_P

Host

PMACK

PARTIAL1

Load/Start

SLUMBER

Timer

SLUMBER timer

Expired

PARTIAL2

Device Init

ACTIVE

State

Device

COMWAKE

ACTIVE4

Device Init

SLUMBER

Send

PMREQ_S

10-5-04

R e c e iv d e

C o m m a n d

No C om man ds P end ing

ACTIVE2

Stop

PARTIAL

Timer

If PARTIAL Disabled

Rx, Tx Start or Host PMNAK

Device Initiated

SATA power management state machine e04149-r0 9

Device Initiated Interface PM

„

Recommended DIPM, Advantages…

†

Easy to implement – Vendor Independent

†

No new commands or Serial Transport functions

†

Actions that may start Device Initiated Interface PM

†

Any SATA specific Phy PM (Shown in state machine)

†

PATA PM Commands (Shown in state machine)

†

Vendor specific drive PM modes

†

ATA Advance Power Management timer (??)

†

Of course host can initiate PM state change anytime

†

Includes PM retry with timers

†

Easily expanded for future mobile enhancements

†

Inter and Intra-command DIPM e04149-r0

10-5-04

10

advertisement

Was this manual useful for you? Yes No
Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Related manuals

Download PDF

advertisement