diff --git a/profiles/input/hog.c b/profiles/input/hog.c
index 91c2802..4647fef 100644
--- a/profiles/input/hog.c
+++ b/profiles/input/hog.c
DBG("uHID event type %d received", ev.type);
switch (ev.type) {
+ case UHID_START:
+ case UHID_STOP:
+ /* These are called to start and stop the underlying hardware.
+ * For HoG we open the channels before creating the device so
+ * the hardware is always ready. No need to handle these.
+ * Note that these are also called when the kernel switches
+ * between device-drivers loaded on the HID device. But we can
+ * simply keep the hardware alive during transitions and it
+ * works just fine.
+ * The kernel never destroys a device itself! Only an explicit
+ * UHID_DESTROY request can remove a device. */
+ break;
+ case UHID_OPEN:
+ case UHID_CLOSE:
+ /* OPEN/CLOSE are sent whenever user-space opens any interface
+ * provided by the kernel HID device. Whenever the open-count
+ * is non-zero we must be ready for I/O. As long as it is zero,
+ * we can decide to drop all I/O and put the device
+ * asleep This is optional, though. Moreover, some
+ * special device drivers are buggy in that regard, so
+ * maybe we just keep I/O always awake like HIDP in the
+ * kernel does. */
+ break;
case UHID_OUTPUT:
case UHID_FEATURE:
forward_report(hogdev, &ev);
break;
case UHID_OUTPUT_EV:
- DBG("uHID output event: type %d code %d value %d",
+ /* This is only sent by kernels prior to linux-3.11. It
+ * requires us to parse HID-descriptors in user-space to
+ * properly handle it. This is redundant as the kernel
+ * does it already. That's why newer kernels assemble
+ * the output-reports and send it to us via UHID_OUTPUT.
+ * We never implemented this, so we rely on users to use
+ * recent-enough kernels if they want this feature. No reason
+ * to implement this for older kernels. */
+ DBG("Unsupported uHID output event: type %d code %d value %d",
ev.u.output_ev.type, ev.u.output_ev.code,
ev.u.output_ev.value);
break;