From a903e442c8e9b9551ad1b31d686153eeba59c0c0 Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Sat, 13 Jul 2024 15:38:21 +0000
Subject: [PATCH] Implement some more suspend/resume Linux compat such that
 inteldrm(4) can achieve RC6 and save a significant amount of power for S0i.

ok jsg@
---
 sys/dev/pci/drm/drm_drv.c                    | 10 ++++++++++
 sys/dev/pci/drm/drm_linux.c                  | 14 +++++++++++++-
 sys/dev/pci/drm/i915/gt/intel_gt_pm.c        |  4 ----
 sys/dev/pci/drm/include/generated/autoconf.h |  1 +
 sys/dev/pci/drm/include/linux/acpi.h         |  3 +++
 sys/dev/pci/drm/include/linux/suspend.h      | 14 ++++++++++++++
 6 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/sys/dev/pci/drm/drm_drv.c b/sys/dev/pci/drm/drm_drv.c
index 4193f4ce1c3..3cf746c6d54 100644
--- a/sys/dev/pci/drm/drm_drv.c
+++ b/sys/dev/pci/drm/drm_drv.c
@@ -47,6 +47,7 @@
 #include <linux/pseudo_fs.h>
 #include <linux/slab.h>
 #include <linux/srcu.h>
+#include <linux/suspend.h>
 
 #include <drm/drm_accel.h>
 #include <drm/drm_cache.h>
@@ -1548,10 +1549,19 @@ drm_activate(struct device *self, int act)
 
 	switch (act) {
 	case DVACT_QUIESCE:
+#ifdef CONFIG_ACPI
+		if (acpi_softc && acpi_softc->sc_state == ACPI_STATE_S3)
+			pm_suspend_target_state = PM_SUSPEND_MEM;
+		else
+			pm_suspend_target_state = PM_SUSPEND_TO_IDLE;
+#else
+		pm_suspend_target_state = PM_SUSPEND_TO_IDLE;
+#endif
 		drm_quiesce(dev);
 		break;
 	case DVACT_WAKEUP:
 		drm_wakeup(dev);
+		pm_suspend_target_state = PM_SUSPEND_ON;
 		break;
 	}
 
diff --git a/sys/dev/pci/drm/drm_linux.c b/sys/dev/pci/drm/drm_linux.c
index 3204b4a0af5..2d3e9196c2b 100644
--- a/sys/dev/pci/drm/drm_linux.c
+++ b/sys/dev/pci/drm/drm_linux.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: drm_linux.c,v 1.114 2024/06/13 18:05:54 kettenis Exp $	*/
+/*	$OpenBSD: drm_linux.c,v 1.115 2024/07/13 15:38:21 kettenis Exp $	*/
 /*
  * Copyright (c) 2013 Jonathan Gray <jsg@openbsd.org>
  * Copyright (c) 2015, 2016 Mark Kettenis <kettenis@openbsd.org>
@@ -51,6 +51,7 @@
 #include <linux/kthread.h>
 #include <linux/processor.h>
 #include <linux/sync_file.h>
+#include <linux/suspend.h>
 
 #include <drm/drm_device.h>
 #include <drm/drm_connector.h>
@@ -1345,6 +1346,8 @@ vga_put(struct pci_dev *pdev, int rsrc)
 
 #endif
 
+suspend_state_t pm_suspend_target_state;
+
 /*
  * ACPI types and interfaces.
  */
@@ -1360,6 +1363,8 @@ vga_put(struct pci_dev *pdev, int rsrc)
 #include <dev/acpi/amltypes.h>
 #include <dev/acpi/dsdt.h>
 
+struct acpi_fadt acpi_gbl_FADT;
+
 acpi_status
 acpi_get_table(const char *sig, int instance,
     struct acpi_table_header **hdr)
@@ -2851,6 +2856,13 @@ drm_linux_init(void)
 
 	kmap_atomic_va =
 	    (vaddr_t)km_alloc(PAGE_SIZE, &kv_any, &kp_none, &kd_waitok);
+
+#if NACPI > 0
+	if (acpi_softc) {
+		memcpy(&acpi_gbl_FADT, acpi_softc->sc_fadt,
+		    sizeof(acpi_gbl_FADT));
+	}
+#endif
 }
 
 void
diff --git a/sys/dev/pci/drm/i915/gt/intel_gt_pm.c b/sys/dev/pci/drm/i915/gt/intel_gt_pm.c
index 84451257e1b..ad361eb56e7 100644
--- a/sys/dev/pci/drm/i915/gt/intel_gt_pm.c
+++ b/sys/dev/pci/drm/i915/gt/intel_gt_pm.c
@@ -326,7 +326,6 @@ void intel_gt_suspend_prepare(struct intel_gt *gt)
 	wait_for_suspend(gt);
 }
 
-#ifdef notyet
 static suspend_state_t pm_suspend_target(void)
 {
 #if IS_ENABLED(CONFIG_SUSPEND) && IS_ENABLED(CONFIG_PM_SLEEP)
@@ -335,7 +334,6 @@ static suspend_state_t pm_suspend_target(void)
 	return PM_SUSPEND_TO_IDLE;
 #endif
 }
-#endif
 
 void intel_gt_suspend_late(struct intel_gt *gt)
 {
@@ -361,10 +359,8 @@ void intel_gt_suspend_late(struct intel_gt *gt)
 	 * powermanagement enabled, but we also retain system state and so
 	 * it remains safe to keep on using our allocated memory.
 	 */
-#ifdef notyet
 	if (pm_suspend_target() == PM_SUSPEND_TO_IDLE)
 		return;
-#endif
 
 	with_intel_runtime_pm(gt->uncore->rpm, wakeref) {
 		intel_rps_disable(&gt->rps);
diff --git a/sys/dev/pci/drm/include/generated/autoconf.h b/sys/dev/pci/drm/include/generated/autoconf.h
index adcef50e28b..9c8565e7862 100644
--- a/sys/dev/pci/drm/include/generated/autoconf.h
+++ b/sys/dev/pci/drm/include/generated/autoconf.h
@@ -93,5 +93,6 @@
 #endif
 
 #if defined(SUSPEND) || defined(HIBERNATE)
+#define CONFIG_SUSPEND				1
 #define CONFIG_PM_SLEEP				1
 #endif
diff --git a/sys/dev/pci/drm/include/linux/acpi.h b/sys/dev/pci/drm/include/linux/acpi.h
index b10d28eaba1..b15702c4687 100644
--- a/sys/dev/pci/drm/include/linux/acpi.h
+++ b/sys/dev/pci/drm/include/linux/acpi.h
@@ -88,4 +88,7 @@ int unregister_acpi_notifier(struct notifier_block *);
 
 int acpi_target_system_state(void);
 
+extern struct acpi_fadt acpi_gbl_FADT;
+#define ACPI_FADT_LOW_POWER_S0		(1 << 21)
+
 #endif
diff --git a/sys/dev/pci/drm/include/linux/suspend.h b/sys/dev/pci/drm/include/linux/suspend.h
index e69de29bb2d..223844e664d 100644
--- a/sys/dev/pci/drm/include/linux/suspend.h
+++ b/sys/dev/pci/drm/include/linux/suspend.h
@@ -0,0 +1,14 @@
+/* Public domain. */
+
+#ifndef _LINUX_SUSPEND_H
+#define _LINUX_SUSPEND_H
+
+typedef int suspend_state_t;
+
+#define PM_SUSPEND_ON		0
+#define PM_SUSPEND_MEM		1
+#define PM_SUSPEND_TO_IDLE	2
+
+extern suspend_state_t pm_suspend_target_state;
+
+#endif
-- 
2.20.1