HID: core: move Usage Page concatenation to Main item
[ Upstream commit 58e75155009cc800005629955d3482f36a1e0eec ]
As seen on some USB wireless keyboards manufactured by Primax, the HID
parser was using some assumptions that are not always true. In this case
it's s the fact that, inside the scope of a main item, an Usage Page
will always precede an Usage.
The spec is not pretty clear as 6.2.2.7 states "Any usage that follows
is interpreted as a Usage ID and concatenated with the Usage Page".
While 6.2.2.8 states "When the parser encounters a main item it
concatenates the last declared Usage Page with a Usage to form a
complete usage value." Being somewhat contradictory it was decided to
match Window's implementation, which follows 6.2.2.8.
In summary, the patch moves the Usage Page concatenation from the local
item parsing function to the main item parsing function.
Change-Id: I6580ed3ca583c740090a8fa9ae9f9ca450da3af0
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Terry Junge <terry.junge@poly.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Git-commit: 58e75155009cc800005629955d3482f36a1e0eec
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
[jianzhou@codeaurora.org: resolved trivial conflict in drivers/hid/hid-core.c]
Signed-off-by: jianzhou <jianzhou@codeaurora.org>
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 332bea8..d1fe7e8 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -200,13 +200,14 @@
* Add a usage to the temporary parser table.
*/
-static int hid_add_usage(struct hid_parser *parser, unsigned usage)
+static int hid_add_usage(struct hid_parser *parser, unsigned usage, u8 size)
{
if (parser->local.usage_index >= HID_MAX_USAGES) {
hid_err(parser->device, "usage index exceeded\n");
return -1;
}
parser->local.usage[parser->local.usage_index] = usage;
+ parser->local.usage_size[parser->local.usage_index] = size;
parser->local.collection_index[parser->local.usage_index] =
parser->collection_stack_ptr ?
parser->collection_stack[parser->collection_stack_ptr - 1] : 0;
@@ -463,10 +464,7 @@
return 0;
}
- if (item->size <= 2)
- data = (parser->global.usage_page << 16) + data;
-
- return hid_add_usage(parser, data);
+ return hid_add_usage(parser, data, item->size);
case HID_LOCAL_ITEM_TAG_USAGE_MINIMUM:
@@ -475,9 +473,6 @@
return 0;
}
- if (item->size <= 2)
- data = (parser->global.usage_page << 16) + data;
-
parser->local.usage_minimum = data;
return 0;
@@ -488,9 +483,6 @@
return 0;
}
- if (item->size <= 2)
- data = (parser->global.usage_page << 16) + data;
-
count = data - parser->local.usage_minimum;
if (count + parser->local.usage_index >= HID_MAX_USAGES) {
/*
@@ -510,7 +502,7 @@
}
for (n = parser->local.usage_minimum; n <= data; n++)
- if (hid_add_usage(parser, n)) {
+ if (hid_add_usage(parser, n, item->size)) {
dbg_hid("hid_add_usage failed\n");
return -1;
}
@@ -525,6 +517,22 @@
}
/*
+ * Concatenate Usage Pages into Usages where relevant:
+ * As per specification, 6.2.2.8: "When the parser encounters a main item it
+ * concatenates the last declared Usage Page with a Usage to form a complete
+ * usage value."
+ */
+
+static void hid_concatenate_usage_page(struct hid_parser *parser)
+{
+ int i;
+
+ 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;
+}
+
+/*
* Process a main item.
*/
@@ -533,6 +541,8 @@
__u32 data;
int ret;
+ hid_concatenate_usage_page(parser);
+
data = item_udata(item);
switch (item->tag) {
@@ -746,6 +756,8 @@
__u32 data;
int i;
+ hid_concatenate_usage_page(parser);
+
data = item_udata(item);
switch (item->tag) {