/* pcm *_ops structures */
-static struct snd_pcm_ops analog_playback_ops = {
+static const struct snd_pcm_ops analog_playback_ops = {
        .open = pcm_analog_out_open,
        .close = pcm_close,
        .ioctl = snd_pcm_lib_ioctl,
        .pointer = pcm_pointer,
        .page = snd_pcm_sgbuf_ops_page,
 };
-static struct snd_pcm_ops analog_capture_ops = {
+static const struct snd_pcm_ops analog_capture_ops = {
        .open = pcm_analog_in_open,
        .close = pcm_close,
        .ioctl = snd_pcm_lib_ioctl,
 };
 #ifdef ECHOCARD_HAS_DIGITAL_IO
 #ifndef ECHOCARD_HAS_VMIXER
-static struct snd_pcm_ops digital_playback_ops = {
+static const struct snd_pcm_ops digital_playback_ops = {
        .open = pcm_digital_out_open,
        .close = pcm_close,
        .ioctl = snd_pcm_lib_ioctl,
        .page = snd_pcm_sgbuf_ops_page,
 };
 #endif /* !ECHOCARD_HAS_VMIXER */
-static struct snd_pcm_ops digital_capture_ops = {
+static const struct snd_pcm_ops digital_capture_ops = {
        .open = pcm_digital_in_open,
        .close = pcm_close,
        .ioctl = snd_pcm_lib_ioctl,