[PATCH 4/6] Input: elantech - work around EC buffer

[JJ Ding]

With some EC chips, when we resync due to bad packets, those bad bytes would
still remain in EC's buffer area. That makes us always get bad data back,
no matter what.

So shift packet for 1 byte when encounter bad packet, until we get rid of those
bytes.

Signed-off-by: JJ Ding <jj_ding@xxxxxxxxxx>
---
 drivers/input/mouse/elantech.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 032181c..7b9b6e5 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -411,20 +411,25 @@ static psmouse_ret_t elantech_process_byte(struct psmouse *psmouse)
 	switch (etd->hw_version) {
 	case 1:
 		if (etd->paritycheck && !elantech_check_parity_v1(psmouse))
-			return PSMOUSE_BAD_DATA;
+			goto bad_packet;
 
 		elantech_report_absolute_v1(psmouse);
 		break;
 
 	case 2:
 		if (etd->paritycheck && !packet_simple_check_v2(psmouse))
-			return PSMOUSE_BAD_DATA;
+			goto bad_packet;
 
 		elantech_report_absolute_v2(psmouse);
 		break;
 	}
 
 	return PSMOUSE_FULL_PACKET;
+
+ bad_packet:
+	memmove(psmouse->packet, psmouse->packet + 1, psmouse->pktsize - 1);
+	psmouse->pktcnt--;
+	return PSMOUSE_GOOD_DATA;
 }
 
 /*
-- 
1.7.4.1

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