[PATCH] fbfront: advertise either absolute or relative coordinates

[Olaf Hering <olaf@aepfle.de>]

A virtualized display device is usually viewed with the vncviewer
application, either by 'xm vnc domU' or with vncviewer localhost:port.
vncviewer and the RFB protocol provides absolute coordinates to the
virtual display. These coordinates are either passed through to a PV
guest or converted to relative coordinates for a HVM guest.

A PV guest receives these coordinates and passes them to the kernels
evdev driver. There it can be picked up by applications such as the
xorg-input drivers. Using absolute coordinates avoids issues such as
guest mouse pointer not tracking host mouse pointer due to wrong mouse
acceleration settings in the guests X display.

Advertise either absolute or relative coordinates to the input system
and the evdev driver, depending on what dom0 provides. The xorg-input
driver prefers relative coordinates even if a devices provides both.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

---
 drivers/xen/fbfront/xenkbd.c |   28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

Index: linux-2.6.18-xen.hg/drivers/xen/fbfront/xenkbd.c
===================================================================
--- linux-2.6.18-xen.hg.orig/drivers/xen/fbfront/xenkbd.c
+++ linux-2.6.18-xen.hg/drivers/xen/fbfront/xenkbd.c
@@ -104,7 +104,7 @@ static irqreturn_t input_handler(int rq,
 int __devinit xenkbd_probe(struct xenbus_device *dev,
 			   const struct xenbus_device_id *id)
 {
-	int ret, i;
+	int ret, i, abs;
 	struct xenkbd_info *info;
 	struct input_dev *kbd, *ptr;
 
@@ -123,6 +123,11 @@ int __devinit xenkbd_probe(struct xenbus
 	info->page->in_cons = info->page->in_prod = 0;
 	info->page->out_cons = info->page->out_prod = 0;
 
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", &abs) < 0)
+		abs = 0;
+	if (abs)
+		xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", "1");
+
 	/* keyboard */
 	kbd = input_allocate_device();
 	if (!kbd)
@@ -155,10 +160,15 @@ int __devinit xenkbd_probe(struct xenbus
 	ptr->id.bustype = BUS_PCI;
 	ptr->id.vendor = 0x5853;
 	ptr->id.product = 0xfffe;
-	ptr->evbit[0] = BIT(EV_KEY) | BIT(EV_REL) | BIT(EV_ABS);
+	ptr->evbit[0] = BIT(EV_KEY);
+	if (abs)
+		ptr->evbit[0] |= BIT(EV_ABS);
+	else {
+		ptr->evbit[0] |= BIT(EV_REL);
+		ptr->relbit[0] = BIT(REL_X) | BIT(REL_Y) | BIT(REL_WHEEL);
+	}
 	for (i = BTN_LEFT; i <= BTN_TASK; i++)
 		set_bit(i, ptr->keybit);
-	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);
 
@@ -263,7 +273,7 @@ static void xenkbd_backend_changed(struc
 				   enum xenbus_state backend_state)
 {
 	struct xenkbd_info *info = dev->dev.driver_data;
-	int ret, val;
+	int val;
 
 	switch (backend_state) {
 	case XenbusStateInitialising:
@@ -276,16 +286,6 @@ static void xenkbd_backend_changed(struc
 
 	case XenbusStateInitWait:
 	InitWait:
-		ret = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-				   "feature-abs-pointer", "%d", &val);
-		if (ret < 0)
-			val = 0;
-		if (val) {
-			ret = xenbus_printf(XBT_NIL, info->xbdev->nodename,
-					    "request-abs-pointer", "1");
-			if (ret)
-				; /* FIXME */
-		}
 		xenbus_switch_state(dev, XenbusStateConnected);
 		break;