Update values from response of URL_DEVICES, callback if changed.

def update_devices(self, devices):
        """Update values from response of URL_DEVICES, callback if changed."""
        for qspacket in devices:
            try:
                qsid = qspacket[QS_ID]
            except KeyError:
                _LOGGER.debug("Device without ID: %s", qspacket)
                continue

            if qsid not in self:
                self[qsid] = QSDev(data=qspacket)

            dev = self[qsid]
            dev.data = qspacket
            # Decode value from QSUSB
            newqs = _legacy_status(qspacket[QS_VALUE])
            if dev.is_dimmer:
                # Adjust dimmer exponentially to get a smoother effect
                newqs = min(round(math.pow(newqs, self.dim_adj)), 100)
            newin = round(newqs * _MAX / 100)
            if abs(dev.value - newin) > 1:  # Significant change
                _LOGGER.debug("%s qs=%s  -->  %s", qsid, newqs, newin)
                dev.value = newin
                self._cb_value_changed(self, qsid, newin)