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    SubjectRe: [patch] My AMD IDE driver, v2.7
    On Tue, 19 Mar 2002 22:56:09 +0100, Vojtech Pavlik wrote:

    >> > Not all of them safely, though. Many a drive will corrupt data if it
    >> > receives a command when not spinned up. You need to issue a wake command
    >> > first, which hdparm doesn't, it just leaves it to the kernel to issue a
    >> > read command or whatever to wake the drive ...
    >>
    >> Is this common disk bug, or are they permitted to behave like that?
    >
    >This behavior is permitted by the specification, as far as I know -

    Actually not. Have a look at page 36 of the current ATA6 specification.


    >results of commands other than wakeup (and other pm commands) in sleep
    >or suspend mode are undefined ...

    If a disk is in power state PM1:idle or PM2:standby, each ATA command
    which requires media access will result in a transition to power state
    PM0:active as well. The driver should be prepared of a long command
    execution time in this case (due to the spin up delay). This is why a
    well implemented ATA driver should track the individual power states of
    each attached unit to modulate its internal command timeout
    accordingly.

    The driver may issue a SET_FEATURES(spin up) command in anticipation of
    a media access. A "forgiving" implementation might issue this command
    at proper system state transitions as well .

    If a disk has entered power state PM3:sleep, its interface is turned
    off! You no longer can issue any command except for a DEVICE RESET to
    this unit. A reset is required to initiate a state transition from
    PM3:sleep to PM2:standby (there are no other state transitions).

    Ciao,
    Dani

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Daniela Engert, systems engineer at MEDAV GmbH
    Gräfenberger Str. 34, 91080 Uttenreuth, Germany
    Phone ++49-9131-583-348, Fax ++49-9131-583-11


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