in this article I found a nice Setting
"WaitForTXcomplete" = "dword:1" ;Default is 1 which means it driver will wait until all data is sent before returning control to the app ;If you set this value to 0, the write function will return before all data is transmitted over the Serial port. ;This can be helpful if you transmit a lot of small packages. Be aware, that the write function doesn't return immediately, ;it returns after it wrote the last data to the transmit buffer.
But this setting is listed for PXA modules.
i.MX7 modules didn’t have this setting?
How behave this modules?
With best regards