[RFC v2 02/10] acpi/x86: s2idle: Move Modern Standby calls to s2idle begin/end

[Antheas Kapenekakis]

In Windows, the modern standby calls for sleep entry/exit and display
on/off happen while the kernel device subsystems are active and the
device is asleep. Currently, in the Linux kernel they happen in
prepare_late, after e.g. the USB subsystem has turned off. This
disimilarity causes obscure issues in certain devices that use these
calls to turn off peripherals that should not be active during modern
standby, e.g. handheld controllers, and RGB.

Therefore, move these calls to _begin(), and _end() to match Windows.
Particularly for _end(), introduce a acpi_s2idle_end_lps0() function to
wrap acpi_s2idle_end(), matching the structure introduced with
acpi_s2idle_begin_lps0().

Of note is that unlike the ACPI ABI of LPS0, there is no device power
state requirement before entering sleep/screen off, therefore it is
appropriate to move these calls to _begin(), before s2idle suspend.

Link: https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/modern-standby-states
Signed-off-by: Antheas Kapenekakis <lkml@xxxxxxxxxxx>
---
 drivers/acpi/x86/s2idle.c | 63 +++++++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 26 deletions(-)

diff --git a/drivers/acpi/x86/s2idle.c b/drivers/acpi/x86/s2idle.c
index 61a044b59776..f5aefba8b191 100644
--- a/drivers/acpi/x86/s2idle.c
+++ b/drivers/acpi/x86/s2idle.c
@@ -517,8 +517,10 @@ static struct acpi_scan_handler lps0_handler = {
 
 static int acpi_s2idle_begin_lps0(void)
 {
-	if (lps0_device_handle && !sleep_no_lps0 && check_lps0_constraints &&
-	    !lpi_constraints_table) {
+	if (!lps0_device_handle || sleep_no_lps0)
+		return acpi_s2idle_begin();
+
+	if (check_lps0_constraints && !lpi_constraints_table) {
 		if (acpi_s2idle_vendor_amd())
 			lpi_device_get_constraints_amd();
 		else
@@ -532,6 +534,24 @@ static int acpi_s2idle_begin_lps0(void)
 			lpi_constraints_table = ERR_PTR(-ENODATA);
 	}
 
+	/* Display off */
+	if (lps0_dsm_func_mask > 0)
+		acpi_sleep_run_lps0_dsm(acpi_s2idle_vendor_amd() ?
+					ACPI_LPS0_DISPLAY_OFF_AMD :
+					ACPI_LPS0_DISPLAY_OFF,
+					lps0_dsm_func_mask, lps0_dsm_guid);
+
+	if (lps0_dsm_func_mask_microsoft > 0)
+		acpi_sleep_run_lps0_dsm(ACPI_LPS0_DISPLAY_OFF,
+					lps0_dsm_func_mask_microsoft,
+					lps0_dsm_guid_microsoft);
+
+	/* Modern Standby entry */
+	if (lps0_dsm_func_mask_microsoft > 0)
+		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SLEEP_ENTRY,
+					lps0_dsm_func_mask_microsoft,
+					lps0_dsm_guid_microsoft);
+
 	return acpi_s2idle_begin();
 }
 
@@ -545,36 +565,17 @@ static int acpi_s2idle_prepare_late_lps0(void)
 	if (check_lps0_constraints)
 		lpi_check_constraints();
 
-	/* Display off */
+	/* LPS0 entry */
 	if (lps0_dsm_func_mask > 0)
 		acpi_sleep_run_lps0_dsm(acpi_s2idle_vendor_amd() ?
-					ACPI_LPS0_DISPLAY_OFF_AMD :
-					ACPI_LPS0_DISPLAY_OFF,
+						ACPI_LPS0_ENTRY_AMD :
+						ACPI_LPS0_ENTRY,
 					lps0_dsm_func_mask, lps0_dsm_guid);
 
 	if (lps0_dsm_func_mask_microsoft > 0)
-		acpi_sleep_run_lps0_dsm(ACPI_LPS0_DISPLAY_OFF,
-					lps0_dsm_func_mask_microsoft,
-					lps0_dsm_guid_microsoft);
-
-	/* LPS0 entry */
-	if (lps0_dsm_func_mask > 0 && acpi_s2idle_vendor_amd())
-		acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY_AMD,
-					lps0_dsm_func_mask, lps0_dsm_guid);
-
-	if (lps0_dsm_func_mask_microsoft > 0) {
-		/* Modern Standby entry */
-		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SLEEP_ENTRY,
-					lps0_dsm_func_mask_microsoft,
-					lps0_dsm_guid_microsoft);
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY,
 					lps0_dsm_func_mask_microsoft,
 					lps0_dsm_guid_microsoft);
-	}
-
-	if (lps0_dsm_func_mask > 0 && !acpi_s2idle_vendor_amd())
-		acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY,
-					lps0_dsm_func_mask, lps0_dsm_guid);
 
 	list_for_each_entry(handler, &lps0_s2idle_devops_head, list_node) {
 		if (handler->prepare)
@@ -615,9 +616,19 @@ static void acpi_s2idle_restore_early_lps0(void)
 					ACPI_LPS0_EXIT,
 					lps0_dsm_func_mask, lps0_dsm_guid);
 
-	if (lps0_dsm_func_mask_microsoft > 0) {
+	if (lps0_dsm_func_mask_microsoft > 0)
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT,
 				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
+}
+
+static void acpi_s2idle_end_lps0(void)
+{
+	acpi_s2idle_end();
+
+	if (!lps0_device_handle || sleep_no_lps0)
+		return;
+
+	if (lps0_dsm_func_mask_microsoft > 0) {
 		/* Intent to turn on display */
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_TURN_ON_DISPLAY,
 					lps0_dsm_func_mask_microsoft,
@@ -648,7 +659,7 @@ static const struct platform_s2idle_ops acpi_s2idle_ops_lps0 = {
 	.wake = acpi_s2idle_wake,
 	.restore_early = acpi_s2idle_restore_early_lps0,
 	.restore = acpi_s2idle_restore,
-	.end = acpi_s2idle_end,
+	.end = acpi_s2idle_end_lps0,
 };
 
 void __init acpi_s2idle_setup(void)
-- 
2.53.0