[ 23/40] HID: Fix Speedlink VAD Cezanne support for some devices

Greg Kroah-Hartman
2013-09-25T01:26:56Z

From: Stefan Kriwanek <dev@stefankriwanek.de>

commit 06bb5219118fb098f4b0c7dcb484b28a52bf1c14 upstream.

Some devices of the "Speedlink VAD Cezanne" model need more aggressive fixing
than already done.

I made sure through testing that this patch would not interfere with the proper
working of a device that is bug-free. (The driver drops EV_REL events with
abs(val) >= 256, which are not achievable even on the highest laser resolution
hardware setting.)

Signed-off-by: Stefan Kriwanek <mail@stefankriwanek.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hid/hid-speedlink.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

--- a/drivers/hid/hid-speedlink.c
+++ b/drivers/hid/hid-speedlink.c
@@ -3,7 +3,7 @@
* Fixes "jumpy" cursor and removes nonexistent keyboard LEDS from
* the HID descriptor.
*
- * Copyright (c) 2011 Stefan Kriwanek <mail@stefankriwanek.de>
+ * Copyright (c) 2011, 2013 Stefan Kriwanek <dev@stefankriwanek.de>
*/

/*
@@ -48,8 +48,13 @@ static int speedlink_event(struct hid_de
struct hid_usage *usage, __s32 value)
{
/* No other conditions due to usage_table. */
- /* Fix "jumpy" cursor (invalid events sent by device). */
- if (value == 256)
+
+ /* This fixes the "jumpy" cursor occuring due to invalid events sent
+ * by the device. Some devices only send them with value==+256, others
+ * don't. However, catching abs(value)>=256 is restrictive enough not
+ * to interfere with devices that were bug-free (has been tested).
+ */
+ if (abs(value) >= 256)
return 1;
/* Drop useless distance 0 events (on button clicks etc.) as well */
if (value == 0)