Commit 7edf6f7e authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

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



Commit 32ece31d ("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: 32ece31d ("ACPI: PM: s2idle: Only retrieve constraints when needed")
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarMario Limonciello (AMD) <superm1@kernel.org>
Link: https://patch.msgid.link/2827214.mvXUDI8C0e@rafael.j.wysocki
parent 8f334e35

drivers/acpi/x86/s2idle.c

+6 −2
Original line number Diff line number Diff line
@@ -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 */