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    rework pm_ops pm_disk_mode, kill misuse · fe0c935a
    Johannes Berg 提交于
    This patch series cleans up some misconceptions about pm_ops.  Some users of
    the pm_ops structure attempt to use it to stop the user from entering suspend
    to disk, this, however, is not possible since the user can always use
    "shutdown" in /sys/power/disk and then the pm_ops are never invoked.  Also,
    platforms that don't support suspend to disk simply should not allow
    configuring SOFTWARE_SUSPEND (read the help text on it, it only selects
    suspend to disk and nothing else, all the other stuff depends on PM).
    
    The pm_ops structure is actually intended to provide a way to enter
    platform-defined sleep states (currently supported states are "standby" and
    "mem" (suspend to ram)) and additionally (if SOFTWARE_SUSPEND is configured)
    allows a platform to support a platform specific way to enter low-power mode
    once everything has been saved to disk.  This is currently only used by ACPI
    (S4).
    
    This patch:
    
    The pm_ops.pm_disk_mode is used in totally bogus ways since nobody really
    seems to understand what it actually does.
    
    This patch clarifies the pm_disk_mode description.
    
    It also removes all the arm and sh users that think they can veto suspend to
    disk via pm_ops; not so since the user can always do echo shutdown >
    /sys/power/disk, they need to find a better way involving Kconfig or such.
    
    ACPI is the only user left with a non-zero pm_disk_mode.
    
    The patch also sets the default mode to shutdown again, but when a new pm_ops
    is registered its pm_disk_mode is selected as default, that way the default
    stays for ACPI where it is apparently required.
    Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
    Cc: David Brownell <david-b@pacbell.net>
    Acked-by: NPavel Machek <pavel@ucw.cz>
    Cc: <linux-pm@lists.linux-foundation.org>
    Cc: Len Brown <lenb@kernel.org>
    Acked-by: NRussell King <rmk@arm.linux.org.uk>
    Cc: Greg KH <greg@kroah.com>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    Acked-by: NPaul Mundt <lethal@linux-sh.org>
    Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    fe0c935a
pm.c 5.5 KB