Re: [PATCH] input/xen-kbdfront: Enable auto repeat for xen keyboard frontend driver

[Dmitry Torokhov]

Hi Liang,

On Wed, Aug 23, 2017 at 02:10:26PM -0400, Liang Yan wrote:
> Long pressed key could not show right in XEN vncviewer after tigervnc
> client changed the way how to send repeat keys, from "Down Up Down Up
> ..." to "Down Down ... Up". By enable EV_REP bit here, XEN keyboard
> device will trigger default auto repeat process from input subsystem,
> and make auto repeat keys work correctly.

I almost applied it, but then I started to wonder: enabling autorepeat
in guest kernel means that autorepeat settings might differ between the
VNC client and the guest. Maybe the better fix would be to actually
assume that backend/client does not send duplicate events, but
autorepeat events, and do the following in xenkbd_handle_key_event():

static void xenkbd_handle_key_event(struct xenkbd_info *info,
                                    struct xenkbd_key *key)
{
        struct input_dev *dev;
        int value = key->pressed;

        if (test_bit(key->keycode, info->ptr->keybit)) {
                dev = info->ptr;
        } else if (test_bit(key->keycode, info->kbd->keybit)) {
                dev = info->kbd;
                /* See if the key is already pressed */
                if (test_bit(key->keycode, info->kbd->key))
                        value = 2; /* Report autorepeat */
        } else {
                pr_warn("unhandled keycode 0x%x\n", key->keycode);
                return;
        }

        input_event(dev, EV_KEY, key->keycode, value);
        input_sync(dev);
}

Thanks.

> 
> Signed-off-by: Liang Yan <l...@suse.com>
> ---
>  drivers/input/misc/xen-kbdfront.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/input/misc/xen-kbdfront.c 
> b/drivers/input/misc/xen-kbdfront.c
> index fa130e7b734c..0dce9830e2f4 100644
> --- a/drivers/input/misc/xen-kbdfront.c
> +++ b/drivers/input/misc/xen-kbdfront.c
> @@ -248,6 +248,7 @@ static int xenkbd_probe(struct xenbus_device *dev,
>       kbd->id.product = 0xffff;
>  
>       __set_bit(EV_KEY, kbd->evbit);
> +     __set_bit(EV_REP, kbd->evbit);
>       for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
>               __set_bit(i, kbd->keybit);
>       for (i = KEY_OK; i < KEY_MAX; i++)
> -- 
> 2.14.1
> 

-- 
Dmitry