1 files changed, 50 insertions, 8 deletions

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 7c8049a5bd99..0c547bf841f4 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -196,6 +196,18 @@ static unsigned hid_lookup_collection(struct hid_parser *parser, unsigned type)
 }
 
 /*
+ * Concatenate usage which defines 16 bits or less with the
+ * currently defined usage page to form a 32 bit usage
+ */
+
+static void complete_usage(struct hid_parser *parser, unsigned int index)
+{
+	parser->local.usage[index] &= 0xFFFF;
+	parser->local.usage[index] |=
+		(parser->global.usage_page & 0xFFFF) << 16;
+}
+
+/*
  * Add a usage to the temporary parser table.
  */
 
@@ -206,6 +218,14 @@ static int hid_add_usage(struct hid_parser *parser, unsigned usage, u8 size)
 		return -1;
 	}
 	parser->local.usage[parser->local.usage_index] = usage;
+
+	/*
+	 * If Usage item only includes usage id, concatenate it with
+	 * currently defined usage page
+	 */
+	if (size <= 2)
+		complete_usage(parser, parser->local.usage_index);
+
 	parser->local.usage_size[parser->local.usage_index] = size;
 	parser->local.collection_index[parser->local.usage_index] =
 		parser->collection_stack_ptr ?
@@ -522,13 +542,32 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
  * usage value."
  */
 
-static void hid_concatenate_usage_page(struct hid_parser *parser)
+static void hid_concatenate_last_usage_page(struct hid_parser *parser)
 {
 	int i;
+	unsigned int usage_page;
+	unsigned int current_page;
 
-	for (i = 0; i < parser->local.usage_index; i++)
-		if (parser->local.usage_size[i] <= 2)
-			parser->local.usage[i] += parser->global.usage_page << 16;
+	if (!parser->local.usage_index)
+		return;
+
+	usage_page = parser->global.usage_page;
+
+	/*
+	 * Concatenate usage page again only if last declared Usage Page
+	 * has not been already used in previous usages concatenation
+	 */
+	for (i = parser->local.usage_index - 1; i >= 0; i--) {
+		if (parser->local.usage_size[i] > 2)
+			/* Ignore extended usages */
+			continue;
+
+		current_page = parser->local.usage[i] >> 16;
+		if (current_page == usage_page)
+			break;
+
+		complete_usage(parser, i);
+	}
 }
 
 /*
@@ -540,7 +579,7 @@ static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
 	__u32 data;
 	int ret;
 
-	hid_concatenate_usage_page(parser);
+	hid_concatenate_last_usage_page(parser);
 
 	data = item_udata(item);
 
@@ -751,7 +790,7 @@ static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
 	__u32 data;
 	int i;
 
-	hid_concatenate_usage_page(parser);
+	hid_concatenate_last_usage_page(parser);
 
 	data = item_udata(item);
 
@@ -979,6 +1018,7 @@ int hid_open_report(struct hid_device *device)
 	__u8 *start;
 	__u8 *buf;
 	__u8 *end;
+	__u8 *next;
 	int ret;
 	static int (*dispatch_type[])(struct hid_parser *parser,
 				      struct hid_item *item) = {
@@ -1032,7 +1072,8 @@ int hid_open_report(struct hid_device *device)
 	device->collection_size = HID_DEFAULT_NUM_COLLECTIONS;
 
 	ret = -EINVAL;
-	while ((start = fetch_item(start, end, &item)) != NULL) {
+	while ((next = fetch_item(start, end, &item)) != NULL) {
+		start = next;
 
 		if (item.format != HID_ITEM_FORMAT_SHORT) {
 			hid_err(device, "unexpected long global item\n");
@@ -1061,7 +1102,8 @@ int hid_open_report(struct hid_device *device)
 		}
 	}
 
-	hid_err(device, "item fetching failed at offset %d\n", (int)(end - start));
+	hid_err(device, "item fetching failed at offset %u/%u\n",
+		size - (unsigned int)(end - start), size);
 err:
 	vfree(parser);
 	hid_close_report(device);