Keep sending signal without sound

I bought Hifiberry a couple days ago. I use it to feed PS audio DL III. The sound is great.
However, I have an issue that Hifiberry won't shut its output while the device is closed.
This is very annoying because PS audio is facing to my bed. The signal makes DAC awake.
Therefore, the blue LED keep emitting light even there is no sound at all. Any reason to keep it alive?
I have done my patch, and it looks very well. Is it possible to commit the change in the future kernel release?
Here is my patch.
40,47c38
< static void snd_rpi_hifiberry_digi_shutdown(struct snd_pcm_substream *substream)
< {
< struct snd_soc_pcm_runtime *rtd = substream->private_data;
< struct snd_soc_codec *codec = rtd->codec;
<
< /* disable TX output */
< snd_soc_update_bits(codec, WM8804_PWRDN, 0x4, 0x4);
< return;
---
> return 0;
107d97
< .shutdown = snd_rpi_hifiberry_digi_shutdown,