“cat: write error: No space left on device” when I write to a character device using “cat”

I am trying to use VS1053, an audio decoder, on Linux 4.14 to play music. This device communicate through SPI bus, and I've developed a driver and registered VS1053 as a character device, thanks for https://github.com/rvp-nl/vs10xx-linux. Here comes the problem.

The way to play music is:

cat musicfile.mp3 > /dev/VS1053_device

When I throw a WAV music file to the device, everything is ok, and music plays well. However, when I throw a mp3 music file to the device, Linux casts an error

cat: write error: No space left on device

I've searched for the reason on many sites. Many said, check free space and free inode on file system, but this is my result:

[email protected]:~# df -i                                                        
Filesystem     Inodes IUsed  IFree IUse% Mounted on                             
/dev/root      956592 10795 945797    2% /                                      
devtmpfs       234285   308 233977    1% /dev                                   
tmpfs          234333   205 234128    1% /run                                   
tmpfs          234333    10 234323    1% /var/volatile                          
[email protected]:~# df -h                                                        
Filesystem      Size  Used Avail Use% Mounted on                                
/dev/root        15G  412M   14G   3% /                                         
devtmpfs        916M     0  916M   0% /dev                                      
tmpfs           916M   84K  916M   1% /run                                      
tmpfs           916M   28K  916M   1% /var/volatile                             
[email protected]:~# 

The music file is limited within 100MB, there is no way that the space is used up.

I tried to write an print file program to substitute "cat", but that doesn't work either. I have no idea why and how this error happened.

I am super grateful if anyone could help me on this!!!