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Device Initiated Power Management, which is defined in SATA 2.5 can be enabled for disks which support it. This patch enables DIPM when the user sets the link power management policy to "min_power". Additionally, libata drivers can define a function (enable_pm) that will perform hardware specific actions to enable whatever power management policy the user set up for Host Initiated Power management (HIPM). This power management policy will be activated after all disks have been enumerated and intialized. Drivers should also define disable_pm, which will turn off link power management, but not change link power management policy. Documentation/scsi/link_power_management_policy.txt has additional information. Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
20 lines
729 B
Plaintext
20 lines
729 B
Plaintext
This parameter allows the user to set the link (interface) power management.
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There are 3 possible options:
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Value Effect
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----------------------------------------------------------------------------
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min_power Tell the controller to try to make the link use the
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least possible power when possible. This may
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sacrifice some performance due to increased latency
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when coming out of lower power states.
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max_performance Generally, this means no power management. Tell
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the controller to have performance be a priority
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over power management.
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medium_power Tell the controller to enter a lower power state
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when possible, but do not enter the lowest power
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state, thus improving latency over min_power setting.
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