From 4ab8f7f320f91f279c3f06a9795cfea5c972888a Mon Sep 17 00:00:00 2001 From: Pali Rohár Date: Sat, 8 Nov 2014 12:45:23 -0800 Subject: Input: alps - ignore potential bare packets when device is out of sync MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5th and 6th byte of ALPS trackstick V3 protocol match condition for first byte of PS/2 3 bytes packet. When driver enters out of sync state and ALPS trackstick is sending data then driver match 5th, 6th and next 1st bytes as PS/2. It basically means if user is using trackstick when driver is in out of sync state driver will never resync. Processing these bytes as 3 bytes PS/2 data cause total mess (random cursor movements, random clicks) and make trackstick unusable until psmouse driver decide to do full device reset. Lot of users reported problems with ALPS devices on Dell Latitude E6440, E6540 and E7440 laptops. ALPS device or Dell EC for unknown reason send some invalid ALPS PS/2 bytes which cause driver out of sync. It looks like that i8042 and psmouse/alps driver always receive group of 6 bytes packets so there are no missing bytes and no bytes were inserted between valid ones. This patch does not fix root of problem with ALPS devices found in Dell Latitude laptops but it does not allow to process some (invalid) subsequence of 6 bytes ALPS packets as 3 bytes PS/2 when driver is out of sync. So with this patch trackstick input device does not report bogus data when also driver is out of sync, so trackstick should be usable on those machines. Signed-off-by: Pali Rohár Tested-by: Pali Rohár Cc: stable@vger.kernel.org Reviewed-by: Hans de Goede Signed-off-by: Dmitry Torokhov --- drivers/input/mouse/alps.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'drivers/input/mouse/alps.c') diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c index 2b0ae8cc8e5..da18c977e7b 100644 --- a/drivers/input/mouse/alps.c +++ b/drivers/input/mouse/alps.c @@ -1156,7 +1156,13 @@ static psmouse_ret_t alps_process_byte(struct psmouse *psmouse) { struct alps_data *priv = psmouse->private; - if ((psmouse->packet[0] & 0xc8) == 0x08) { /* PS/2 packet */ + /* + * Check if we are dealing with a bare PS/2 packet, presumably from + * a device connected to the external PS/2 port. Because bare PS/2 + * protocol does not have enough constant bits to self-synchronize + * properly we only do this if the device is fully synchronized. + */ + if (!psmouse->out_of_sync_cnt && (psmouse->packet[0] & 0xc8) == 0x08) { if (psmouse->pktcnt == 3) { alps_report_bare_ps2_packet(psmouse, psmouse->packet, true); -- cgit v1.2.3-70-g09d2 From 9d720b34c0a432639252f63012e18b0507f5b432 Mon Sep 17 00:00:00 2001 From: Pali Rohár Date: Sat, 8 Nov 2014 12:58:57 -0800 Subject: Input: alps - allow up to 2 invalid packets without resetting device MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On some Dell Latitude laptops ALPS device or Dell EC send one invalid byte in 6 bytes ALPS packet. In this case psmouse driver enter out of sync state. It looks like that all other bytes in packets are valid and also device working properly. So there is no need to do full device reset, just need to wait for byte which match condition for first byte (start of packet). Because ALPS packets are bigger (6 or 8 bytes) default limit is small. This patch increase number of invalid bytes to size of 2 ALPS packets which psmouse driver can drop before do full reset. Resetting ALPS devices take some time and when doing reset on some Dell laptops touchpad, trackstick and also keyboard do not respond. So it is better to do it only if really necessary. Signed-off-by: Pali Rohár Tested-by: Pali Rohár Reviewed-by: Hans de Goede Cc: stable@vger.kernel.org Signed-off-by: Dmitry Torokhov --- drivers/input/mouse/alps.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/input/mouse/alps.c') diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c index da18c977e7b..433638e7e4a 100644 --- a/drivers/input/mouse/alps.c +++ b/drivers/input/mouse/alps.c @@ -2395,6 +2395,9 @@ int alps_init(struct psmouse *psmouse) /* We are having trouble resyncing ALPS touchpads so disable it for now */ psmouse->resync_time = 0; + /* Allow 2 invalid packets without resetting device */ + psmouse->resetafter = psmouse->pktsize * 2; + return 0; init_fail: -- cgit v1.2.3-70-g09d2 From a7ef82aee91f26da79b981b9f5bca43b8817d3e4 Mon Sep 17 00:00:00 2001 From: Pali Rohár Date: Sat, 8 Nov 2014 23:36:09 -0800 Subject: Input: alps - ignore bad data on Dell Latitudes E6440 and E7440 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sometimes on Dell Latitude laptops psmouse/alps driver receive invalid ALPS protocol V3 packets with bit7 set in last byte. More often it can be reproduced on Dell Latitude E6440 or E7440 with closed lid and pushing cover above touchpad. If bit7 in last packet byte is set then it is not valid ALPS packet. I was told that ALPS devices never send these packets. It is not know yet who send those packets, it could be Dell EC, bug in BIOS and also bug in touchpad firmware... With this patch alps driver does not process those invalid packets, but instead of reporting PSMOUSE_BAD_DATA, getting into out of sync state, getting back in sync with the next byte and spam dmesg we return PSMOUSE_FULL_PACKET. If driver is truly out of sync we'll fail the checks on the next byte and report PSMOUSE_BAD_DATA then. Signed-off-by: Pali Rohár Tested-by: Pali Rohár Cc: stable@vger.kernel.org Signed-off-by: Dmitry Torokhov --- drivers/input/mouse/alps.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'drivers/input/mouse/alps.c') diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c index 433638e7e4a..d125a019383 100644 --- a/drivers/input/mouse/alps.c +++ b/drivers/input/mouse/alps.c @@ -1186,12 +1186,27 @@ static psmouse_ret_t alps_process_byte(struct psmouse *psmouse) } /* Bytes 2 - pktsize should have 0 in the highest bit */ - if ((priv->proto_version < ALPS_PROTO_V5) && + if (priv->proto_version < ALPS_PROTO_V5 && psmouse->pktcnt >= 2 && psmouse->pktcnt <= psmouse->pktsize && (psmouse->packet[psmouse->pktcnt - 1] & 0x80)) { psmouse_dbg(psmouse, "refusing packet[%i] = %x\n", psmouse->pktcnt - 1, psmouse->packet[psmouse->pktcnt - 1]); + + if (priv->proto_version == ALPS_PROTO_V3 && + psmouse->pktcnt == psmouse->pktsize) { + /* + * Some Dell boxes, such as Latitude E6440 or E7440 + * with closed lid, quite often smash last byte of + * otherwise valid packet with 0xff. Given that the + * next packet is very likely to be valid let's + * report PSMOUSE_FULL_PACKET but not process data, + * rather than reporting PSMOUSE_BAD_DATA and + * filling the logs. + */ + return PSMOUSE_FULL_PACKET; + } + return PSMOUSE_BAD_DATA; } -- cgit v1.2.3-70-g09d2