This is a note to let you know that I've just added the patch titled Input: alps - v7: ignore new packets to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: input-alps-v7-ignore-new-packets.patch and it can be found in the queue-3.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 8b23811535d2e1dd6abbe4ce6ea1edfd50ce72de Mon Sep 17 00:00:00 2001 From: Hans de Goede <hdegoede@xxxxxxxxxx> Date: Thu, 18 Dec 2014 09:52:59 -0800 Subject: Input: alps - v7: ignore new packets From: Hans de Goede <hdegoede@xxxxxxxxxx> commit 8b23811535d2e1dd6abbe4ce6ea1edfd50ce72de upstream. NEW packets are send to indicate a discontinuity in the finger coordinate reporting. Specifically a finger may have moved from slot 0 to 1 or vice versa. INPUT_MT_TRACK takes care of this for us. NEW packets have 3 problems: 1) They do not contain middle / right button info (on non clickpads) this can be worked around by preserving the old button state 2) They do not contain an accurate fingercount, and they are typically send when the number of fingers changes. We cannot use the old finger count as that may mismatch with the amount of touch coordinates we've available in the NEW packet 3) Their x data for the second touch is inaccurate leading to a possible jump of the x coordinate by 16 units when the first non NEW packet comes in Since problems 2 & 3 cannot be worked around, just ignore them. BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=86338 Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> Tested-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/input/mouse/alps.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) --- a/drivers/input/mouse/alps.c +++ b/drivers/input/mouse/alps.c @@ -938,18 +938,36 @@ static int alps_decode_packet_v7(struct return 0; if (pkt_id == V7_PACKET_ID_UNKNOWN) return -1; + /* + * NEW packets are send to indicate a discontinuity in the finger + * coordinate reporting. Specifically a finger may have moved from + * slot 0 to 1 or vice versa. INPUT_MT_TRACK takes care of this for + * us. + * + * NEW packets have 3 problems: + * 1) They do not contain middle / right button info (on non clickpads) + * this can be worked around by preserving the old button state + * 2) They do not contain an accurate fingercount, and they are + * typically send when the number of fingers changes. We cannot use + * the old finger count as that may mismatch with the amount of + * touch coordinates we've available in the NEW packet + * 3) Their x data for the second touch is inaccurate leading to + * a possible jump of the x coordinate by 16 units when the first + * non NEW packet comes in + * Since problems 2 & 3 cannot be worked around, just ignore them. + */ + if (pkt_id == V7_PACKET_ID_NEW) + return 1; alps_get_finger_coordinate_v7(f->mt, p, pkt_id); - if (pkt_id == V7_PACKET_ID_TWO || pkt_id == V7_PACKET_ID_MULTI) { - f->left = (p[0] & 0x80) >> 7; - f->right = (p[0] & 0x20) >> 5; - f->middle = (p[0] & 0x10) >> 4; - } + f->left = (p[0] & 0x80) >> 7; + f->right = (p[0] & 0x20) >> 5; + f->middle = (p[0] & 0x10) >> 4; if (pkt_id == V7_PACKET_ID_TWO) f->fingers = alps_get_mt_count(f->mt); - else if (pkt_id == V7_PACKET_ID_MULTI) + else /* pkt_id == V7_PACKET_ID_MULTI */ f->fingers = 3 + (p[5] & 0x03); return 0; Patches currently in stable-queue which might be from hdegoede@xxxxxxxxxx are queue-3.18/input-alps-v7-ignore-new-packets.patch queue-3.18/input-alps-v7-sometimes-a-single-touch-is-reported-in-mt.patch queue-3.18/input-alps-v7-fix-finger-counting-for-2-fingers-on-clickpads.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html