Eric Lee / smarc-ti-linux-kernel

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Commit 98eb06b6ca5f9e41356d51847912da48d9da3508

Authored by Hans de Goede
Committed by Greg Kroah-Hartman
1 parent 3dcf157fe8

Input: alps - v7: ignore new packets 

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@redhat.com>
Tested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 24 additions and 6 deletions Side-by-side Diff

drivers/input/mouse/alps.c
Diff comments   View file @ 98eb06b
... ... @@ -938,18 +938,36 @@
938 938 return 0;
939 939 if (pkt_id == V7_PACKET_ID_UNKNOWN)
940 940 return -1;
  941 + /*
  942 + * NEW packets are send to indicate a discontinuity in the finger
  943 + * coordinate reporting. Specifically a finger may have moved from
  944 + * slot 0 to 1 or vice versa. INPUT_MT_TRACK takes care of this for
  945 + * us.
  946 + *
  947 + * NEW packets have 3 problems:
  948 + * 1) They do not contain middle / right button info (on non clickpads)
  949 + * this can be worked around by preserving the old button state
  950 + * 2) They do not contain an accurate fingercount, and they are
  951 + * typically send when the number of fingers changes. We cannot use
  952 + * the old finger count as that may mismatch with the amount of
  953 + * touch coordinates we've available in the NEW packet
  954 + * 3) Their x data for the second touch is inaccurate leading to
  955 + * a possible jump of the x coordinate by 16 units when the first
  956 + * non NEW packet comes in
  957 + * Since problems 2 & 3 cannot be worked around, just ignore them.
  958 + */
  959 + if (pkt_id == V7_PACKET_ID_NEW)
  960 + return 1;
941 961  
942 962 alps_get_finger_coordinate_v7(f->mt, p, pkt_id);
943 963  
944   - if (pkt_id == V7_PACKET_ID_TWO || pkt_id == V7_PACKET_ID_MULTI) {
945   - f->left = (p[0] & 0x80) >> 7;
946   - f->right = (p[0] & 0x20) >> 5;
947   - f->middle = (p[0] & 0x10) >> 4;
948   - }
  964 + f->left = (p[0] & 0x80) >> 7;
  965 + f->right = (p[0] & 0x20) >> 5;
  966 + f->middle = (p[0] & 0x10) >> 4;
949 967  
950 968 if (pkt_id == V7_PACKET_ID_TWO)
951 969 f->fingers = alps_get_mt_count(f->mt);
952   - else if (pkt_id == V7_PACKET_ID_MULTI)
  970 + else /* pkt_id == V7_PACKET_ID_MULTI */
953 971 f->fingers = 3 + (p[5] & 0x03);
954 972  
955 973 return 0;