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ACPI: PM: s2idle: Add module parameter for LPS0 constraints checking

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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
This commit is contained in:
Rafael J. Wysocki
2026-01-13 14:36:54 +01:00
parent 8f334e3522
commit 7edf6f7ef5
1 changed files with 6 additions and 2 deletions
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8
drivers/acpi/x86/s2idle.c
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@@ -28,6 +28,10 @@ static bool sleep_no_lps0 __read_mostly;
module_param(sleep_no_lps0, bool, 0644);
MODULE_PARM_DESC(sleep_no_lps0, "Do not use the special LPS0 device interface");
static bool check_lps0_constraints __read_mostly;
module_param(check_lps0_constraints, bool, 0644);
MODULE_PARM_DESC(check_lps0_constraints, "Check LPS0 device constraints");
static const struct acpi_device_id lps0_device_ids[] = {
{"PNP0D80", },
{"", },
@@ -515,7 +519,7 @@ static struct acpi_scan_handler lps0_handler = {
static int acpi_s2idle_begin_lps0(void)
{
if (lps0_device_handle && !sleep_no_lps0 && pm_debug_messages_on &&
if (lps0_device_handle && !sleep_no_lps0 && check_lps0_constraints &&
!lpi_constraints_table) {
if (acpi_s2idle_vendor_amd())
lpi_device_get_constraints_amd();
@@ -540,7 +544,7 @@ static int acpi_s2idle_prepare_late_lps0(void)
if (!lps0_device_handle || sleep_no_lps0)
return 0;
if (pm_debug_messages_on)
if (check_lps0_constraints)
lpi_check_constraints();
/* Screen off */