Commit 32ece31db4 ("ACPI: PM: s2idle: Only retrieve constraints when
needed") attempted to avoid useless evaluation of LPS0 _DSM Function 1
in lps0_device_attach() because pm_debug_messages_on might never be set
(and that is the case on production systems most of the time), but it
turns out that LPS0 _DSM Function 1 is generally problematic on some
platforms and causes suspend issues to occur when pm_debug_messages_on
is set now.
In Linux, LPS0 _DSM Function 1 is only useful for diagnostics and only
in the cases when the system does not reach the deepest platform idle
state during suspend-to-idle for some reason. If such diagnostics is
not necessary, evaluating it is a loss of time, so using it along with
the other pm_debug_messages_on diagnostics is questionable because the
latter is expected to be suitable for collecting debug information even
during production use of system suspend.
For this reason, add a module parameter called check_lps0_constraints
to control whether or not the list of LPS0 constraints will be checked
in acpi_s2idle_prepare_late_lps0() and so whether or not to evaluate
LPS0 _DSM Function 1 (once) in acpi_s2idle_begin_lps0().
Fixes: 32ece31db4 ("ACPI: PM: s2idle: Only retrieve constraints when needed")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Link: https://patch.msgid.link/2827214.mvXUDI8C0e@rafael.j.wysocki
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