From: Phillip Susi <psusi@ubuntu.com>
To: linux-ide@vger.kernel.org
Subject: Understanding staggered spinup
Date: Tue, 24 Sep 2013 10:56:48 -0400 [thread overview]
Message-ID: <5241A830.7030903@ubuntu.com> (raw)
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I was looking at the libata code that handles the ahci staggered
spinup feature ( SSS ) and am confused as to how this feature can
possibly work. Cross referencing the AHCI spec with the code, it
seems that the feature simply delays sending COMRESET and initializing
the sata link until we set the SUD bit rather than at power on.
According to the ATA specs though, a drive that powers up in standby
will remain there until given an explicit command ( either SET
FEATURES or a command that requires media access ). In other words,
COMRESET will not cause the drive to spin up.
Does this feature not really work or am I missing something?
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reply other threads:[~2013-09-24 17:02 UTC|newest]
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