[RFC 2/2] drm/i915/dgfx: Runtime resume the dgpu on user fault

[Anshuman Gupta <anshuman.gupta@xxxxxxxxx>]

Runtime resume the dgpu(when gem object lies in lmem).
This will transition the dgpu graphics function to D0
state if it was in D3 in order to access the mmap memory
mappings.

Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Anshuman Gupta <anshuman.gupta@xxxxxxxxx>
---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index b49823d599e7..1e9b07473a8f 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -1020,6 +1020,7 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
 	struct ttm_buffer_object *bo = area->vm_private_data;
 	struct drm_device *dev = bo->base.dev;
 	struct drm_i915_gem_object *obj;
+	intel_wakeref_t wakeref = 0;
 	vm_fault_t ret;
 	int idx;
 
@@ -1027,18 +1028,24 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
 	if (!obj)
 		return VM_FAULT_SIGBUS;
 
+	if (i915_gem_object_is_lmem(obj))
+		wakeref = intel_runtime_pm_get(&to_i915(obj->base.dev)->runtime_pm);
+
 	/* Sanity check that we allow writing into this object */
 	if (unlikely(i915_gem_object_is_readonly(obj) &&
-		     area->vm_flags & VM_WRITE))
-		return VM_FAULT_SIGBUS;
+		     area->vm_flags & VM_WRITE)) {
+		ret = VM_FAULT_SIGBUS;
+		goto out_rpm;
+	}
 
 	ret = ttm_bo_vm_reserve(bo, vmf);
 	if (ret)
-		return ret;
+		goto out_rpm;
 
 	if (obj->mm.madv != I915_MADV_WILLNEED) {
 		dma_resv_unlock(bo->base.resv);
-		return VM_FAULT_SIGBUS;
+		ret = VM_FAULT_SIGBUS;
+		goto out_rpm;
 	}
 
 	if (!i915_ttm_resource_mappable(bo->resource)) {
@@ -1062,7 +1069,8 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
 		if (err) {
 			drm_dbg(dev, "Unable to make resource CPU accessible\n");
 			dma_resv_unlock(bo->base.resv);
-			return VM_FAULT_SIGBUS;
+			ret = VM_FAULT_SIGBUS;
+			goto out_rpm;
 		}
 	}
 
@@ -1078,11 +1086,16 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
 		list_add(&obj->userfault_link, &to_gt(to_i915(obj->base.dev))->lmem_userfault_list);
 
 	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
-		return ret;
+		goto out_rpm;
 
 	i915_ttm_adjust_lru(obj);
 
 	dma_resv_unlock(bo->base.resv);
+
+out_rpm:
+	if (wakeref)
+		intel_runtime_pm_put(&to_i915(obj->base.dev)->runtime_pm, wakeref);
+
 	return ret;
 }
 
-- 
2.26.2