How to change HDMI volume and play mixing wave1 with wave2 by util aplay

[win77man]

I Need your support
 I have a board "IMX6QP SabreSD" but I had got a problem

 Development environment:
  1. IMX6QP SabreSD (Board)
  2. fsl-yocto-L3.14.52_1.1.0-ga (Linux)
  4. HDMI 1920 x 1080 @60p RGB24  (fb1)

question:
  1. How to change "HDMI" volume level by debug console
  2. How to playing by util "aplay" with mixing wave1.wave & wave2.wave

     Fist I try below

     Play wave1.wav by "aplay" with "aplay wave1.wav -D plughw:1,0"

         and Play wave2.wav by "aplay wave2.wav -D plughw:1,0" for mixing

        But Did not play wave2.wav file because Hdmi port playing wave1.wav by "aplay",

        "Hdmi used already aplay wave1.wav"

Please give me how to do?

[Bio_TICFSL]

Hello

Please update your BSP since several bugs has fixed regarding HDMI volume:

ENGR00178468. HDMI Audio sometimes underrun! and then TV no music output mode 720P after switch different sample rate. 50%

ENGR00178531. HDMI audio played format is too few

ENGR00179425. Sometime HDMI mode is wrong and audio device  gotten is wrong

linux specifics for audio in hdmi is described in sect.6.4.6.6 Audio on the Linux Manual.

HDMI hardware supports audio only in modes given in Table 33-3. Video Modes

i.MX 6Dual/6Quad Applications Processor Reference Manual

Regards