getting the right and complete firmware

[Anil Duggirala]

upon installing Debian stretch I got a notice about missing firmware (Atheros). 
I managed to find a package that, apperently, contained some of the missing 
firmware, since the list of missing firmware was diminished. I am still missing 
some firmware, I will find it eventually, but my question is: Can I be sure I 
have the correct and required firmware if I am not getting any errors from 
dmesg ? or upon boot?
Is there any tool that will help me address these issues?
thanks,