HTC Desire 820 is launched back in 2014 with Snapdragon 615 chipset and 2GB of RAM inside, Now this phone is getting Android 6.0.1 Marshmallow with HTC’s user interface HTC Sense 7.
However, we don’t know clearly which regions are getting this marshmallow update. But the update will include all the basic features of Android marshmallow like Doze, Now on Tap, Runtime Permissions and Google Now on Tap.
As we all know that the firmware updates are usually rolled out in phases. So don’t panic, it you did not get the OTA notification yet, it will come to you in a few days. Meanwhile, you can check for the update manually by going through the settings of your Phone.