Re: [PATCH v3 2/2] Input: xen-kbdfront - allow better run-time configuration

From: Dmitry Torokhov
Date: Wed May 16 2018 - 12:42:59 EST


Hi Oleksandr,

On Mon, May 14, 2018 at 05:40:29PM +0300, Oleksandr Andrushchenko wrote:
> @@ -211,93 +220,114 @@ static int xenkbd_probe(struct xenbus_device *dev,
> if (!info->page)
> goto error_nomem;
>
> - /* Set input abs params to match backend screen res */
> - abs = xenbus_read_unsigned(dev->otherend,
> - XENKBD_FIELD_FEAT_ABS_POINTER, 0);
> - ptr_size[KPARAM_X] = xenbus_read_unsigned(dev->otherend,
> - XENKBD_FIELD_WIDTH,
> - ptr_size[KPARAM_X]);
> - ptr_size[KPARAM_Y] = xenbus_read_unsigned(dev->otherend,
> - XENKBD_FIELD_HEIGHT,
> - ptr_size[KPARAM_Y]);
> - if (abs) {
> - ret = xenbus_write(XBT_NIL, dev->nodename,
> - XENKBD_FIELD_REQ_ABS_POINTER, "1");
> - if (ret) {
> - pr_warn("xenkbd: can't request abs-pointer\n");
> - abs = 0;
> - }
> - }
> + /*
> + * The below are reverse logic, e.g. if the feature is set, then
> + * do not expose the corresponding virtual device.
> + */
> + with_kbd = !xenbus_read_unsigned(dev->nodename,
> + XENKBD_FIELD_FEAT_DSBL_KEYBRD, 0);
>
> - touch = xenbus_read_unsigned(dev->nodename,
> - XENKBD_FIELD_FEAT_MTOUCH, 0);
> - if (touch) {
> + with_ptr = !xenbus_read_unsigned(dev->nodename,
> + XENKBD_FIELD_FEAT_DSBL_POINTER, 0);
> +
> + /* Direct logic: if set, then create multi-touch device. */
> + with_mtouch = xenbus_read_unsigned(dev->nodename,
> + XENKBD_FIELD_FEAT_MTOUCH, 0);
> + if (with_mtouch) {
> ret = xenbus_write(XBT_NIL, dev->nodename,
> XENKBD_FIELD_REQ_MTOUCH, "1");
> if (ret) {
> pr_warn("xenkbd: can't request multi-touch");
> - touch = 0;
> + with_mtouch = 0;
> }
> }

Does it make sense to still end up calling xenkbd_connect_backend() when
all interfaces (keyboard, pointer, and multitouch) are disabled? Should
we do:

if (!(with_kbd || || with_ptr || with_mtouch))
return -ENXIO;

?

Thanks.

--
Dmitry