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authorNicolas Saenz Julienne <nsaenzjulienne@suse.de>2019-03-27 13:18:48 +0300
committerBenjamin Tissoires <benjamin.tissoires@redhat.com>2019-04-02 17:09:35 +0300
commit58e75155009cc800005629955d3482f36a1e0eec (patch)
tree17cc4d9277a06263cd2f70d4711b0f766d0b9562 /drivers/hid/hid-core.c
parentc6400e5cef5eafc259e649ceedc4c7eecc9069d8 (diff)
downloadlinux-58e75155009cc800005629955d3482f36a1e0eec.tar.xz
HID: core: move Usage Page concatenation to Main item
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. 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>
Diffstat (limited to 'drivers/hid/hid-core.c')
-rw-r--r--drivers/hid/hid-core.c36
1 files changed, 24 insertions, 12 deletions
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 9993b692598f..852bbd303d9a 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -218,13 +218,14 @@ static unsigned hid_lookup_collection(struct hid_parser *parser, unsigned type)
* 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;
@@ -486,10 +487,7 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
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:
@@ -498,9 +496,6 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
return 0;
}
- if (item->size <= 2)
- data = (parser->global.usage_page << 16) + data;
-
parser->local.usage_minimum = data;
return 0;
@@ -511,9 +506,6 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
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) {
/*
@@ -533,7 +525,7 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
}
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;
}
@@ -548,6 +540,22 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
}
/*
+ * 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.
*/
@@ -556,6 +564,8 @@ static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
__u32 data;
int ret;
+ hid_concatenate_usage_page(parser);
+
data = item_udata(item);
switch (item->tag) {
@@ -765,6 +775,8 @@ static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
__u32 data;
int i;
+ hid_concatenate_usage_page(parser);
+
data = item_udata(item);
switch (item->tag) {