[PATCH 3/6] Input: elantech - packet checking for v2 hardware

JJ Ding
2011-08-18T01:55:35Z

For v2 hardware, there is no real parity check, but we can still check
some constant bits for data integrity.

Signed-off-by: JJ Ding <jj_ding@emc.com.tw>
---
drivers/input/mouse/elantech.c | 26 +++++++++++++++++++++++---
1 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index cf41f23..032181c 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -376,6 +376,25 @@ static int elantech_check_parity_v1(struct psmouse *psmouse)
etd->parity[packet[3]] == p3;
}

+static int packet_simple_check_v2(struct psmouse *psmouse)
+{
+ struct elantech_data *etd = psmouse->private;
+ unsigned char *packet = psmouse->packet;
+
+ if (etd->reports_pressure)
+ return (packet[0] & 0x0c) == 0x04 &&
+ (packet[3] & 0x0f) == 0x02;
+
+ if ((packet[0] & 0xc0) == 0x80)
+ return (packet[0] & 0x0c) == 0x0c &&
+ (packet[3] & 0x0e) == 0x08;
+
+ return (packet[0] & 0x3c) == 0x3c &&
+ (packet[1] & 0xf0) == 0x00 &&
+ (packet[3] & 0x3e) == 0x38 &&
+ (packet[4] & 0xf0) == 0x00;
+}
+
/*
* Process byte stream from mouse and handle complete packets
*/
@@ -398,7 +417,9 @@ static psmouse_ret_t elantech_process_byte(struct psmouse *psmouse)
break;

case 2:
- /* We don't know how to check parity in protocol v2 */
+ if (etd->paritycheck && !packet_simple_check_v2(psmouse))
+ return PSMOUSE_BAD_DATA;
+
elantech_report_absolute_v2(psmouse);
break;
}
@@ -799,8 +820,7 @@ int elantech_init(struct psmouse *psmouse)
etd->hw_version = 2;
/* For now show extra debug information */
etd->debug = 1;
- /* Don't know how to do parity checking for version 2 */
- etd->paritycheck = 0;
+ etd->paritycheck = 1;

if (etd->fw_version >= 0x020800)
etd->reports_pressure = true;
--
1.7.4.1