[PATCH v2] HID: core: simplify active collection tracking

[Philipp Zabel <philipp.zabel@xxxxxxxxx>]

Manually tracking an active collection to set collection parents is not
necessary, we just have to look one step back into the collection stack
to find the correct parent.

Signed-off-by: Philipp Zabel <philipp.zabel@xxxxxxxxx>
---
Changes since v1:
 - Rebased onto commit ee46967fc6e ("HID: core: replace the collection tree
   pointers with indices").
---
 drivers/hid/hid-core.c | 13 ++-----------
 include/linux/hid.h    |  1 -
 2 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index f9093dedf647..9993b692598f 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -173,8 +173,8 @@ static int open_collection(struct hid_parser *parser, unsigned type)
 	collection->type = type;
 	collection->usage = usage;
 	collection->level = parser->collection_stack_ptr - 1;
-	collection->parent_idx = parser->active_collection_idx;
-	parser->active_collection_idx = collection_index;
+	collection->parent_idx = (collection->level == 0) ? -1 :
+		parser->collection_stack[collection->level - 1];
 
 	if (type == HID_COLLECTION_APPLICATION)
 		parser->device->maxapplication++;
@@ -193,13 +193,6 @@ static int close_collection(struct hid_parser *parser)
 		return -EINVAL;
 	}
 	parser->collection_stack_ptr--;
-	if (parser->active_collection_idx != -1) {
-		struct hid_device *device = parser->device;
-		struct hid_collection *c;
-
-		c = &device->collection[parser->active_collection_idx];
-		parser->active_collection_idx = c->parent_idx;
-	}
 	return 0;
 }
 
@@ -825,7 +818,6 @@ static int hid_scan_report(struct hid_device *hid)
 		return -ENOMEM;
 
 	parser->device = hid;
-	parser->active_collection_idx = -1;
 	hid->group = HID_GROUP_GENERIC;
 
 	/*
@@ -1179,7 +1171,6 @@ int hid_open_report(struct hid_device *device)
 	}
 
 	parser->device = device;
-	parser->active_collection_idx = -1;
 
 	end = start + size;
 
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 992bbb7196df..f9707d1dcb58 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -658,7 +658,6 @@ struct hid_parser {
 	unsigned int         *collection_stack;
 	unsigned int          collection_stack_ptr;
 	unsigned int          collection_stack_size;
-	int                   active_collection_idx; /* device->collection */
 	struct hid_device    *device;
 	unsigned int          scan_flags;
 };
-- 
2.20.1