• Rafael J. Wysocki's avatar
    PM / sleep: System sleep state selection interface rework · 406e7938
    Rafael J. Wysocki authored
    There are systems in which the platform doesn't support any special
    sleep states, so suspend-to-idle (PM_SUSPEND_FREEZE) is the only
    available system sleep state.  However, some user space frameworks
    only use the "mem" and (sometimes) "standby" sleep state labels, so
    the users of those systems need to modify user space in order to be
    able to use system suspend at all and that may be a pain in practice.
    
    Commit 0399d4db (PM / sleep: Introduce command line argument for
    sleep state enumeration) attempted to address this problem by adding
    a command line argument to change the meaning of the "mem" string in
    /sys/power/state to make it trigger suspend-to-idle (instead of
    suspend-to-RAM).
    
    However, there also are systems in which the platform does support
    special sleep states, but suspend-to-idle is the preferred one anyway
    (it even may save more energy than the platform-provided sleep states
    in some cases) and the above commit doesn't help in those cases.
    
    For this reason, rework the system sleep state selection interface
    again (but preserve backwards compatibiliby).  Namely, add a new
    sysfs file, /sys/power/mem_sleep, that will control the system
    suspend mode triggered by writing "mem" to /sys/power/state (in
    analogy with what /sys/power/disk does for hibernation).  Make it
    select suspend-to-RAM ("deep" sleep) by default (if supported) and
    fall back to suspend-to-idle ("s2idle") otherwise and add a new
    command line argument, mem_sleep_default, allowing that default to
    be overridden if need be.
    
    At the same time, drop the relative_sleep_states command line
    argument that doesn't make sense any more.
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Tested-by: default avatarMario Limonciello <mario.limonciello@dell.com>
    406e7938
states.txt 6.09 KB