[Xen-devel] PVFB wheel events (z-axis)

[Markus Armbruster <armbru@xxxxxxxxxx>]

I got questions on this changeset:

    changeset:   354:c3ff0b26f664
    date:        Mon Dec 10 13:52:47 2007 +0000

    Decode mouse event packet dz value and passes it as a wheel event into
    the input stream.

    Signed-off-by: Pat Campbell <plc@xxxxxxxxxx>

    diff -r 7232a025140f -r c3ff0b26f664 drivers/xen/fbfront/xenkbd.c
    --- a/drivers/xen/fbfront/xenkbd.c  Mon Dec 10 13:51:57 2007 +0000
    +++ b/drivers/xen/fbfront/xenkbd.c  Mon Dec 10 13:52:47 2007 +0000
    @@ -64,8 +64,13 @@ static irqreturn_t input_handler(int rq,
                    dev = info->ptr;
                    switch (event->type) {
                    case XENKBD_TYPE_MOTION:
    -                   input_report_rel(dev, REL_X, event->motion.rel_x);
    -                   input_report_rel(dev, REL_Y, event->motion.rel_y);
    +                   if ( event->motion.rel_z == 1 || event->motion.rel_z == 
-1 ) {
    +                           input_report_rel(dev, REL_WHEEL, 0 - 
event->motion.rel_z);
    +                   }           
    +                   else {
    +                           input_report_rel(dev, REL_X, 
event->motion.rel_x);
    +                           input_report_rel(dev, REL_Y, 
event->motion.rel_y);
    +                   }

I don't understand the conditional.  Why is rel_z to be used *only*
when it's 1 or -1, and why are rel_x and rel_y to be used *only* when
rel_z isn't?  That sure is a weird protocol, and it isn't documented
anywhere...

                            break;
                    case XENKBD_TYPE_KEY:
                            dev = NULL;
    @@ -81,8 +86,13 @@ static irqreturn_t input_handler(int rq,
                                           event->key.keycode);
                            break;
                    case XENKBD_TYPE_POS:
    -                   input_report_abs(dev, ABS_X, event->pos.abs_x);
    -                   input_report_abs(dev, ABS_Y, event->pos.abs_y);
    +                   if ( event->pos.abs_z == 1 || event->pos.abs_z == -1 ) {
    +                           input_report_rel(dev, REL_WHEEL, 0 - 
event->pos.abs_z);
    +                   }
    +                   else {
    +                           input_report_abs(dev, ABS_X, event->pos.abs_x);
    +                           input_report_abs(dev, ABS_Y, event->pos.abs_y);
    +                   }

And why isn't this using REL_ABS?

                            break;
                    }
                    if (dev)
    @@ -152,7 +162,7 @@ int __devinit xenkbd_probe(struct xenbus
            ptr->evbit[0] = BIT(EV_KEY) | BIT(EV_REL) | BIT(EV_ABS);
            for (i = BTN_LEFT; i <= BTN_TASK; i++)
                    set_bit(i, ptr->keybit);
    -   ptr->relbit[0] = BIT(REL_X) | BIT(REL_Y);
    +   ptr->relbit[0] = BIT(REL_X) | BIT(REL_Y) | BIT(REL_WHEEL);
            input_set_abs_params(ptr, ABS_X, 0, XENFB_WIDTH, 0, 0);
            input_set_abs_params(ptr, ABS_Y, 0, XENFB_HEIGHT, 0, 0);


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