+/* Stream disable request timeout during USB device disconnect */
+#define DEV_RELEASE_WAIT_TIMEOUT 10000 /* in ms */

10s really? That seems rather large for a stream disable timeout...

+static struct snd_usb_platform_ops offload_ops = {
+	.connect_cb = qc_usb_audio_offload_probe,
+	.disconnect_cb = qc_usb_audio_offload_disconnect,
+	.suspend_cb = qc_usb_audio_offload_suspend,
+};

You probably want to explain why there's no .resume_cb?

The comments mention also that the suspend_cb has to stop playback, but
then who resumes playback :-)