[PATCH v1 3/4] acpi/x86: s2idle: call screen on and off as part of callbacks

[Antheas Kapenekakis <lkml@antheas.dev>]

Move the screen on and off calls into dedicated callbacks that gate
the ACPI mutex, so they can be called outside of the suspend path.
This fixes issues on certain devices that expect kernel drivers to be
fully active during the calls, and allows for the flexibility of calling
them as part of a more elaborate userspace suspend sequence (such as
with "Screen Off" in Windows Modern Standby).

Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
---
 drivers/acpi/x86/s2idle.c | 72 +++++++++++++++++++++++++++++++--------
 1 file changed, 57 insertions(+), 15 deletions(-)

diff --git a/drivers/acpi/x86/s2idle.c b/drivers/acpi/x86/s2idle.c
index dd0b40b9bbe8..aa448ed58077 100644
--- a/drivers/acpi/x86/s2idle.c
+++ b/drivers/acpi/x86/s2idle.c
@@ -60,6 +60,7 @@ static int lps0_dsm_func_mask;
 static guid_t lps0_dsm_guid_microsoft;
 static int lps0_dsm_func_mask_microsoft;
 static int lps0_dsm_state;
+static bool lsp0_dsm_in_screen_off;
 
 /* Device constraint entry structure */
 struct lpi_device_info {
@@ -539,15 +540,19 @@ static struct acpi_scan_handler lps0_handler = {
 	.attach = lps0_device_attach,
 };
 
-int acpi_s2idle_prepare_late(void)
+static int acpi_s2idle_screen_off(void)
 {
-	struct acpi_s2idle_dev_ops *handler;
-
 	if (!lps0_device_handle || sleep_no_lps0)
 		return 0;
 
-	if (pm_debug_messages_on)
-		lpi_check_constraints();
+	if (lsp0_dsm_in_screen_off) {
+		acpi_handle_info(lps0_device_handle,
+				"called screen off call twice before calling screen on.\n");
+		// fallthrough for debugging, calling twice should be gated by the caller
+	}
+
+	lsp0_dsm_in_screen_off = true;
+	acpi_scan_lock_acquire();
 
 	/* Screen off */
 	if (lps0_dsm_func_mask > 0)
@@ -560,6 +565,50 @@ int acpi_s2idle_prepare_late(void)
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_OFF,
 				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
 
+	acpi_scan_lock_release();
+
+	return 0;
+}
+
+static int acpi_s2idle_screen_on(void)
+{
+	if (!lps0_device_handle || sleep_no_lps0)
+		return 0;
+
+	if (!lsp0_dsm_in_screen_off) {
+		acpi_handle_info(lps0_device_handle,
+				"called screen on before calling screen off.\n");
+		// fallthrough for debugging, calling twice should be gated by the caller
+	}
+
+	lsp0_dsm_in_screen_off = false;
+	acpi_scan_lock_acquire();
+
+	/* Screen on */
+	if (lps0_dsm_func_mask_microsoft > 0)
+		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON,
+				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
+	if (lps0_dsm_func_mask > 0)
+		acpi_sleep_run_lps0_dsm(acpi_s2idle_vendor_amd() ?
+					ACPI_LPS0_SCREEN_ON_AMD :
+					ACPI_LPS0_SCREEN_ON,
+					lps0_dsm_func_mask, lps0_dsm_guid);
+
+	acpi_scan_lock_release();
+
+	return 0;
+}
+
+int acpi_s2idle_prepare_late(void)
+{
+	struct acpi_s2idle_dev_ops *handler;
+
+	if (!lps0_device_handle || sleep_no_lps0)
+		return 0;
+
+	if (pm_debug_messages_on)
+		lpi_check_constraints();
+
 	/* LPS0 entry */
 	if (lps0_dsm_func_mask > 0 && acpi_s2idle_vendor_amd())
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY_AMD,
@@ -623,19 +672,10 @@ void acpi_s2idle_restore_early(void)
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_MS_EXIT,
 				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
 	}
-
-	/* Screen on */
-	if (lps0_dsm_func_mask_microsoft > 0)
-		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON,
-				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
-	if (lps0_dsm_func_mask > 0)
-		acpi_sleep_run_lps0_dsm(acpi_s2idle_vendor_amd() ?
-					ACPI_LPS0_SCREEN_ON_AMD :
-					ACPI_LPS0_SCREEN_ON,
-					lps0_dsm_func_mask, lps0_dsm_guid);
 }
 
 static const struct platform_s2idle_ops acpi_s2idle_ops_lps0 = {
+	.screen_off = acpi_s2idle_screen_off,
 	.begin = acpi_s2idle_begin,
 	.prepare = acpi_s2idle_prepare,
 	.prepare_late = acpi_s2idle_prepare_late,
@@ -644,10 +684,12 @@ static const struct platform_s2idle_ops acpi_s2idle_ops_lps0 = {
 	.restore_early = acpi_s2idle_restore_early,
 	.restore = acpi_s2idle_restore,
 	.end = acpi_s2idle_end,
+	.screen_on = acpi_s2idle_screen_on,
 };
 
 void __init acpi_s2idle_setup(void)
 {
+	lsp0_dsm_in_screen_off = false;
 	acpi_scan_add_handler(&lps0_handler);
 	s2idle_set_ops(&acpi_s2idle_ops_lps0);
 }
-- 
2.46.1