CSR, device firmware upgrade problem

Hi All,

This is for CSR, device firmware upgrade problem:

1. In most case, it seems we don't have to update boot loader, right ? so, I can implement H4 for easier. :D
2. I am a little confusing, we just do a upgrade, DFU not like the FLASH rom upgrade, just read and write.

I mean, in my imaginings, it should like below:

===> DFU mode. ===> DFU_UPLOAD ===>DFU_UPLOAD_DATA DFU_UPLOAD_DATA DFU_RESET