ATA_LPM_UNKNOWN
if (policy >= ATA_LPM_UNKNOWN && policy <= ATA_LPM_MIN_POWER)
if (WARN_ON_ONCE(policy == ATA_LPM_UNKNOWN))
link->lpm_policy = ATA_LPM_UNKNOWN; /* reset LPM state */
[ATA_LPM_UNKNOWN] = "keep_firmware_settings",