[PATCH] drm/i915: Exprimental resume speedup.

[Thomas Hellström]

v2:
- Rely on retained ptes to also speed up suspend and resume re-binding.
- Re-build GGTT ptes if intel rst is enabled.

Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
---
 drivers/gpu/drm/i915/gt/intel_ggtt.c | 31 +++++++++++++++++++++++-----
 drivers/gpu/drm/i915/gt/intel_gtt.h  | 17 +++++++++++++++
 drivers/gpu/drm/i915/i915_driver.c   | 11 ++++++++++
 3 files changed, 54 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
index 04191fe2ee34..aa854bc52243 100644
--- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
@@ -23,6 +23,13 @@
 #include "intel_gtt.h"
 #include "gen8_ppgtt.h"
 
+static inline bool suspend_retains_ptes(struct i915_address_space *vm)
+{
+	return GRAPHICS_VER(vm->i915) >= 8 &&
+		!HAS_LMEM(vm->i915) &&
+		vm->is_ggtt;
+}
+
 static void i915_ggtt_color_adjust(const struct drm_mm_node *node,
 				   unsigned long color,
 				   u64 *start,
@@ -179,7 +186,8 @@ void i915_ggtt_suspend_vm(struct i915_address_space *vm)
 		i915_gem_object_unlock(obj);
 	}
 
-	vm->clear_range(vm, 0, vm->total);
+	if (!suspend_retains_ptes(vm))
+		vm->clear_range(vm, 0, vm->total);
 
 	vm->skip_pte_rewrite = save_skip_rewrite;
 
@@ -1180,6 +1188,8 @@ static int i915_gmch_probe(struct i915_ggtt *ggtt)
 		ggtt->do_idle_maps = true;
 	}
 
+	ggtt->pte_lost = true;
+
 	ggtt->vm.insert_page = i915_ggtt_insert_page;
 	ggtt->vm.insert_entries = i915_ggtt_insert_entries;
 	ggtt->vm.clear_range = i915_ggtt_clear_range;
@@ -1309,11 +1319,16 @@ bool i915_ggtt_resume_vm(struct i915_address_space *vm)
 {
 	struct i915_vma *vma;
 	bool write_domain_objs = false;
+	bool retained_ptes;
 
 	drm_WARN_ON(&vm->i915->drm, !vm->is_ggtt && !vm->is_dpt);
 
 	/* First fill our portion of the GTT with scratch pages */
-	vm->clear_range(vm, 0, vm->total);
+	retained_ptes = suspend_retains_ptes(vm) &&
+		!i915_vm_to_ggtt(vm)->pte_lost;
+
+	if (!retained_ptes)
+		vm->clear_range(vm, 0, vm->total);
 
 	/* clflush objects bound into the GGTT and rebind them. */
 	list_for_each_entry(vma, &vm->bound_list, vm_link) {
@@ -1322,9 +1337,10 @@ bool i915_ggtt_resume_vm(struct i915_address_space *vm)
 			atomic_read(&vma->flags) & I915_VMA_BIND_MASK;
 
 		GEM_BUG_ON(!was_bound);
-		vma->ops->bind_vma(vm, NULL, vma->resource,
-				   obj ? obj->cache_level : 0,
-				   was_bound);
+		if (!retained_ptes)
+			vma->ops->bind_vma(vm, NULL, vma->resource,
+					   obj ? obj->cache_level : 0,
+					   was_bound);
 		if (obj) { /* only used during resume => exclusive access */
 			write_domain_objs |= fetch_and_zero(&obj->write_domain);
 			obj->read_domains |= I915_GEM_DOMAIN_GTT;
@@ -1352,3 +1368,8 @@ void i915_ggtt_resume(struct i915_ggtt *ggtt)
 
 	intel_ggtt_restore_fences(ggtt);
 }
+
+void i915_ggtt_mark_pte_lost(struct drm_i915_private *i915, bool val)
+{
+	to_gt(i915)->ggtt->pte_lost = val;
+}
diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
index 4529b5e9f6e6..1459b70bdb5a 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.h
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
@@ -345,6 +345,12 @@ struct i915_ggtt {
 
 	bool do_idle_maps;
 
+	/**
+	 * Whether the system was recently restored from hibernate and
+	 * thus may have lost pte content.
+	 */
+	bool pte_lost;
+
 	int mtrr;
 
 	/** Bit 6 swizzling required for X tiling */
@@ -571,6 +577,17 @@ bool i915_ggtt_resume_vm(struct i915_address_space *vm);
 void i915_ggtt_suspend(struct i915_ggtt *gtt);
 void i915_ggtt_resume(struct i915_ggtt *ggtt);
 
+/**
+ * i915_ggtt_mark_pte_lost - Mark ggtt ptes as lost or clear such a marking
+ * @i915 The device private.
+ * @val whether the ptes should be marked as lost.
+ *
+ * In some cases pte content is retained across suspend, but typically lost
+ * across hibernate. Typically they should be marked as lost on
+ * hibernation restore and such marking cleared on suspend.
+ */
+void i915_ggtt_mark_pte_lost(struct drm_i915_private *i915, bool val);
+
 void
 fill_page_dma(struct drm_i915_gem_object *p, const u64 val, unsigned int count);
 
diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
index 64e6f76861f9..346b7723eb67 100644
--- a/drivers/gpu/drm/i915/i915_driver.c
+++ b/drivers/gpu/drm/i915/i915_driver.c
@@ -98,6 +98,9 @@
 #include "intel_region_ttm.h"
 #include "vlv_suspend.h"
 
+/* Intel Rapid Start Technology ACPI device name */
+static const char irst_name[] = "INT3392";
+
 static const struct drm_driver i915_drm_driver;
 
 static int i915_get_bridge_dev(struct drm_i915_private *dev_priv)
@@ -1425,6 +1428,8 @@ static int i915_pm_suspend(struct device *kdev)
 		return -ENODEV;
 	}
 
+	i915_ggtt_mark_pte_lost(i915, false);
+
 	if (i915->drm.switch_power_state == DRM_SWITCH_POWER_OFF)
 		return 0;
 
@@ -1477,6 +1482,9 @@ static int i915_pm_resume(struct device *kdev)
 	if (i915->drm.switch_power_state == DRM_SWITCH_POWER_OFF)
 		return 0;
 
+	if (GEM_WARN_ON(acpi_dev_present(irst_name, NULL, -1)))
+		i915_ggtt_mark_pte_lost(i915, true);
+
 	return i915_drm_resume(&i915->drm);
 }
 
@@ -1536,6 +1544,9 @@ static int i915_pm_restore_early(struct device *kdev)
 
 static int i915_pm_restore(struct device *kdev)
 {
+	struct drm_i915_private *i915 = kdev_to_i915(kdev);
+
+	i915_ggtt_mark_pte_lost(i915, true);
 	return i915_pm_resume(kdev);
 }
 
-- 
2.34.1