On Friday 03 October 2014 11:51:22 Hans de Goede wrote:

Hi,

On 10/03/2014 11:43 AM, Pali Rohár wrote:

quoted

Sometimes laptops with closed lid receive invalid ALPS
protocol V3 packets with last bit7 set.

This happens on Dell Latitude laptops and it looks like it
is BIOS bug. Probably EC does not correctly split keyboard
and touchpad PS/2 data and when laptop lid is closed it
adds 0xFF packet into touchpad PS/2 data.

When last packet's bit7 is set it is invalid ALPS packet. So
Do not process it and drop it with PSMOUSE_FULL_PACKET.

After testing it looks like this patch fixed problem with
reseting mouse (after series of invalid packets) when
laptop lid is closed on Dell Latitude machines.

Signed-off-by: Pali Rohár <redacted>
Tested-by: Pali Rohár <redacted>
---

 drivers/input/mouse/alps.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/input/mouse/alps.c

b/drivers/input/mouse/alps.c index 1bd5aa1..b1f44d4 100644

--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c

@@ -1179,6 +1179,16 @@ static psmouse_ret_t

alps_process_byte(struct psmouse *psmouse)

 		return PSMOUSE_BAD_DATA;
 	
 	}

+	if (priv->proto_version == ALPS_PROTO_V3 &&
psmouse->pktcnt == psmouse->pktsize) { +		// For protocol
V3, do not process data when last packet's bit7 is set
+		if (psmouse->packet[psmouse->pktcnt - 1] & 0x80) {
+			psmouse_dbg(psmouse, "v3 discard packet[%i] = 

%x\n",

quoted

+				    psmouse->pktcnt - 1,
+				    psmouse->packet[psmouse->pktcnt - 1]);
+			return PSMOUSE_FULL_PACKET;
+		}
+	}
+

I wonder if this should not be PSMOUSE_BAD_DATA as a return
value ? I realize that with the 3th patch in place, that will
cause an immediate reset, but if your theory is right that
this ff gets inserted from the keyboard ps/2 stream, then we
actually want a full reset as otherwise we will be out of
sync then.

We really do not know what is root cause of this problem. 
Probably it is BIOS/EC/firmware/... but it could be something 
other too.

On my laptop - Dell Latitude E6440 - I'm getting these invalid 
packets when I close LID. And they are generated too many (lot of 
per second). When PSMOUSE_FULL_PACKET is returned then no driver 
does not reset touchpad. With PSMOUSE_BAD_DATA psmouse decide 
that it needs reset and with 3rd patch psmouse could try to reset 
device too many times... So I think PSMOUSE_FULL_PACKET is better 
here. And having dmesg log full of device resets is probably not 
good too when laptop lid is closed.

quoted

 	/* Bytes 2 - pktsize should have 0 in the highest bit */
 	if ((priv->proto_version < ALPS_PROTO_V5) &&
 	
 	    psmouse->pktcnt >= 2 && psmouse->pktcnt <=
 	    psmouse->pktsize &&

Regards,

Hans

-- 
Pali Rohár
pali.rohar@gmail.com