lkml.org 
[lkml]   [2004]   [Jun]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 2.6] Mousedev - better button handling under load
    Date
    Hi,

    Currently mousedev combines all hardware motion data that arrivers since
    last time userspace read data into one cooked PS/2 packet. The problem is
    that under heavy or even moderate load, when userspace can't read data
    quickly enough, we start loosing valuable data which manifests in:

    - ignoring buton presses as by the time userspace gets to read the data
    button has already been released;
    - click starts in wrong place - by the time userspace got aroungd and read
    the packet mouse moved half way across the screen.

    The patch below corrects the issue - it will start accumulating new packet
    every time userspace is behind and button set changes. Size of the buffer
    is 16 packets, i.e. up to 8 pairs of press/release events which should be
    more than enough.

    The patch is against Vojtech's tree and shuld apply to -mm. I also have
    cumulative mousedev patch done against 2.6.7-pre2 at:

    http://www.geocities.com/dt_or/input/misc/mousedev-2.6.7-rc2-cumulative.patch.gz

    --
    Dmitry


    ===================================================================


    ChangeSet@1.1828, 2004-06-05 01:05:50-05:00, dtor_core@ameritech.net
    Input: mousedev - better handle button presses when under load

    Signed-off-by: Dmitry Torokhov <dtor@mail.ru>


    mousedev.c | 152 +++++++++++++++++++++++++++++++++++++++++--------------------
    1 files changed, 104 insertions(+), 48 deletions(-)


    ===================================================================



    diff -Nru a/drivers/input/mousedev.c b/drivers/input/mousedev.c
    --- a/drivers/input/mousedev.c 2004-06-05 02:08:31 -05:00
    +++ b/drivers/input/mousedev.c 2004-06-05 02:08:31 -05:00
    @@ -50,6 +50,7 @@

    struct mousedev_motion {
    int dx, dy, dz;
    + unsigned long buttons;
    };

    struct mousedev {
    @@ -62,21 +63,31 @@
    struct input_handle handle;

    struct mousedev_motion packet;
    - unsigned long buttons;
    unsigned int pkt_count;
    int old_x[4], old_y[4];
    unsigned int touch;
    };

    +enum mousedev_emul {
    + MOUSEDEV_EMUL_PS2,
    + MOUSEDEV_EMUL_IMPS,
    + MOUSEDEV_EMUL_EXPS
    +} __attribute__ ((packed));
    +
    +#define PACKET_QUEUE_LEN 16
    struct mousedev_list {
    struct fasync_struct *fasync;
    struct mousedev *mousedev;
    struct list_head node;
    - int dx, dy, dz;
    - unsigned long buttons;
    +
    + struct mousedev_motion packets[PACKET_QUEUE_LEN];
    + unsigned int head, tail;
    + spinlock_t packet_lock;
    +
    signed char ps2[6];
    unsigned char ready, buffer, bufsiz;
    - unsigned char mode, imexseq, impsseq;
    + unsigned char imexseq, impsseq;
    + enum mousedev_emul mode;
    };

    #define MOUSEDEV_SEQ_LEN 6
    @@ -165,24 +176,40 @@
    }

    if (value) {
    - set_bit(index, &mousedev->buttons);
    - set_bit(index, &mousedev_mix.buttons);
    + set_bit(index, &mousedev->packet.buttons);
    + set_bit(index, &mousedev_mix.packet.buttons);
    } else {
    - clear_bit(index, &mousedev->buttons);
    - clear_bit(index, &mousedev_mix.buttons);
    + clear_bit(index, &mousedev->packet.buttons);
    + clear_bit(index, &mousedev_mix.packet.buttons);
    }
    }

    static void mousedev_notify_readers(struct mousedev *mousedev, struct mousedev_motion *packet)
    {
    struct mousedev_list *list;
    + struct mousedev_motion *p;
    + unsigned long flags;

    list_for_each_entry(list, &mousedev->list, node) {
    - list->dx += packet->dx;
    - list->dy += packet->dy;
    - list->dz += packet->dz;
    - list->buttons = mousedev->buttons;
    + spin_lock_irqsave(&list->packet_lock, flags);
    +
    + p = &list->packets[list->head];
    + if (list->ready && p->buttons != packet->buttons) {
    + unsigned int new_head = (list->head + 1) % PACKET_QUEUE_LEN;
    + if (new_head != list->tail) {
    + p = &list->packets[list->head = new_head];
    + memset(p, 0, sizeof(struct mousedev_motion));
    + }
    + }
    +
    + p->dx += packet->dx;
    + p->dy += packet->dy;
    + p->dz += packet->dz;
    + p->buttons = mousedev->packet.buttons;
    +
    list->ready = 1;
    +
    + spin_unlock_irqrestore(&list->packet_lock, flags);
    kill_fasync(&list->fasync, SIGIO, POLL_IN);
    }

    @@ -237,7 +264,7 @@
    mousedev_notify_readers(mousedev, &mousedev->packet);
    mousedev_notify_readers(&mousedev_mix, &mousedev->packet);

    - memset(&mousedev->packet, 0, sizeof(struct mousedev_motion));
    + mousedev->packet.dx = mousedev->packet.dy = mousedev->packet.dz = 0;
    }
    break;
    }
    @@ -322,6 +349,7 @@
    return -ENOMEM;
    memset(list, 0, sizeof(struct mousedev_list));

    + spin_lock_init(&list->packet_lock);
    list->mousedev = mousedev_table[i];
    list_add_tail(&list->node, &mousedev_table[i]->list);
    file->private_data = list;
    @@ -341,32 +369,56 @@
    return 0;
    }

    -static void mousedev_packet(struct mousedev_list *list, unsigned char off)
    +static inline int mousedev_limit_delta(int delta, int limit)
    {
    - list->ps2[off] = 0x08 | ((list->dx < 0) << 4) | ((list->dy < 0) << 5) | (list->buttons & 0x07);
    - list->ps2[off + 1] = (list->dx > 127 ? 127 : (list->dx < -127 ? -127 : list->dx));
    - list->ps2[off + 2] = (list->dy > 127 ? 127 : (list->dy < -127 ? -127 : list->dy));
    - list->dx -= list->ps2[off + 1];
    - list->dy -= list->ps2[off + 2];
    - list->bufsiz = off + 3;
    -
    - if (list->mode == 2) {
    - list->ps2[off + 3] = (list->dz > 7 ? 7 : (list->dz < -7 ? -7 : list->dz));
    - list->dz -= list->ps2[off + 3];
    - list->ps2[off + 3] = (list->ps2[off + 3] & 0x0f) | ((list->buttons & 0x18) << 1);
    - list->bufsiz++;
    - } else {
    - list->ps2[off] |= ((list->buttons & 0x10) >> 3) | ((list->buttons & 0x08) >> 1);
    + return delta > limit ? limit : (delta < -limit ? -limit : delta);
    +}
    +
    +static void mousedev_packet(struct mousedev_list *list, signed char *ps2_data)
    +{
    + struct mousedev_motion *p;
    + unsigned long flags;
    +
    + spin_lock_irqsave(&list->packet_lock, flags);
    + p = &list->packets[list->tail];
    +
    + ps2_data[0] = 0x08 | ((p->dx < 0) << 4) | ((p->dy < 0) << 5) | (p->buttons & 0x07);
    + ps2_data[1] = mousedev_limit_delta(p->dx, 127);
    + ps2_data[2] = mousedev_limit_delta(p->dy, 127);
    + p->dx -= ps2_data[1];
    + p->dy -= ps2_data[2];
    +
    + switch (list->mode) {
    + case MOUSEDEV_EMUL_EXPS:
    + ps2_data[3] = mousedev_limit_delta(p->dz, 127);
    + p->dz -= ps2_data[3];
    + ps2_data[3] = (ps2_data[3] & 0x0f) | ((p->buttons & 0x18) << 1);
    + list->bufsiz = 4;
    + break;
    +
    + case MOUSEDEV_EMUL_IMPS:
    + ps2_data[0] |= ((p->buttons & 0x10) >> 3) | ((p->buttons & 0x08) >> 1);
    + ps2_data[3] = mousedev_limit_delta(p->dz, 127);
    + p->dz -= ps2_data[3];
    + list->bufsiz = 4;
    + break;
    +
    + case MOUSEDEV_EMUL_PS2:
    + default:
    + ps2_data[0] |= ((p->buttons & 0x10) >> 3) | ((p->buttons & 0x08) >> 1);
    + p->dz = 0;
    + list->bufsiz = 3;
    + break;
    }

    - if (list->mode == 1) {
    - list->ps2[off + 3] = (list->dz > 127 ? 127 : (list->dz < -127 ? -127 : list->dz));
    - list->dz -= list->ps2[off + 3];
    - list->bufsiz++;
    + if (!p->dx && !p->dy && !p->dz) {
    + if (list->tail != list->head)
    + list->tail = (list->tail + 1) % PACKET_QUEUE_LEN;
    + if (list->tail == list->head)
    + list->ready = 0;
    }

    - if (!list->dx && !list->dy && (!list->mode || !list->dz)) list->ready = 0;
    - list->buffer = list->bufsiz;
    + spin_unlock_irqrestore(&list->packet_lock, flags);
    }


    @@ -384,31 +436,31 @@
    if (c == mousedev_imex_seq[list->imexseq]) {
    if (++list->imexseq == MOUSEDEV_SEQ_LEN) {
    list->imexseq = 0;
    - list->mode = 2;
    + list->mode = MOUSEDEV_EMUL_EXPS;
    }
    } else list->imexseq = 0;

    if (c == mousedev_imps_seq[list->impsseq]) {
    if (++list->impsseq == MOUSEDEV_SEQ_LEN) {
    list->impsseq = 0;
    - list->mode = 1;
    + list->mode = MOUSEDEV_EMUL_IMPS;
    }
    } else list->impsseq = 0;

    list->ps2[0] = 0xfa;
    - list->bufsiz = 1;

    switch (c) {

    case 0xeb: /* Poll */
    - mousedev_packet(list, 1);
    + mousedev_packet(list, &list->ps2[1]);
    + list->bufsiz++; /* account for leading ACK */
    break;

    case 0xf2: /* Get ID */
    switch (list->mode) {
    - case 0: list->ps2[1] = 0; break;
    - case 1: list->ps2[1] = 3; break;
    - case 2: list->ps2[1] = 4; break;
    + case MOUSEDEV_EMUL_PS2: list->ps2[1] = 0; break;
    + case MOUSEDEV_EMUL_IMPS: list->ps2[1] = 3; break;
    + case MOUSEDEV_EMUL_EXPS: list->ps2[1] = 4; break;
    }
    list->bufsiz = 2;
    break;
    @@ -419,13 +471,15 @@
    break;

    case 0xff: /* Reset */
    - list->impsseq = 0;
    - list->imexseq = 0;
    - list->mode = 0;
    - list->ps2[1] = 0xaa;
    - list->ps2[2] = 0x00;
    + list->impsseq = list->imexseq = 0;
    + list->mode = MOUSEDEV_EMUL_PS2;
    + list->ps2[1] = 0xaa; list->ps2[2] = 0x00;
    list->bufsiz = 3;
    break;
    +
    + default:
    + list->bufsiz = 1;
    + break;
    }

    list->buffer = list->bufsiz;
    @@ -451,8 +505,10 @@
    if (retval)
    return retval;

    - if (!list->buffer && list->ready)
    - mousedev_packet(list, 0);
    + if (!list->buffer && list->ready) {
    + mousedev_packet(list, list->ps2);
    + list->buffer = list->bufsiz;
    + }

    if (count > list->buffer)
    count = list->buffer;
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/
    \
     
     \ /
      Last update: 2005-03-22 14:03    [W:0.041 / U:31.856 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site