Do android phones have hardware chips for encryption? If it's software only, then what is the performance/battery impact? Do android phones have hardware support for the OOTB full phone encryption or is it entirely done in software?

If there are phones which have hardware support for encryption then where could I find a list?

In case if it is purely software then what how much degradation I can expect in terms of performance and battery life?

This and this articles claim that encryption comes at a significant performance price.

And this XDA thread suggests that samsung phones might have dedicated encryption chips as part of their proprietary(?) On-Device Encryption. Is there a clear answer available as to which devices have what support?

Update

I have found a thorough explanation on the state of android hardware encryption support in this article, which says that google failed to introduce proper hardware support in Android 5.x, and then, for android 6.x they decided to go with 'software acceleration' whatever that means.

The article quotes Dave Burke, Google’s engineering lead as saying that:


  “Encryption is software accelerated. Specifically the ARMv8 as part of 64-bit support has a number of instructions that provides better performance than the AES hardware options on the SoC.”


Yet, on the practical side: full disk encryption on android 7.x is faster than on 6.x but the performance hit can still be between 2x to 4x slower compared to an unencrypted phone.
The Android Open Source Project has a entire section on Security:

https://source.android.com/security/

As you asking about encryption the minimum standard for devices with Google Play services is defined by the Android Compatibility Definition Document:

https://source.android.com/compatibility/8.0/android-8.0-cdd#9_9_data_storage_encryption

While there doesn't appear to be any hardware mandates there, once you get to Keystore related items:

https://source.android.com/compatibility/8.0/android-8.0-cdd#9_11_keys_and_credentials

Provided solutions include Trusty which a separate microprocessor or virtualized instance separated from the rest of the Android OS and only accessible via a Hardware Abstraction Layer (HAL).

With regards to Full Disk/File Encryption, see:

https://source.android.com/security/encryption/full-disk