driver-only-builds: enhancing section on removing CIPHER_C
Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/docs/driver-only-builds.md b/docs/driver-only-builds.md
index 05bffa5..7b4b480 100644
--- a/docs/driver-only-builds.md
+++ b/docs/driver-only-builds.md
@@ -331,12 +331,17 @@
### Disabling CIPHER_C
-This is possible when:
+This only depends on unauthenticated ciphers: they can be either completely
+accelerated or disabled in order to remove the dependency on `MBEDTLS_CIPHER_C`.
-- all ciphers and AEADs are accelerated, or
-- no legacy module, either cipher or AEAD, is enabled. The only exception being
- CCM/GCM when key types are accelerated, as described in section
- [Partial acceleration for CCM/GCM](#partial-acceleration-for-CCM/GCM).
+AEADs do not have such restriction. Of course they can be accelerated as well,
+but they can also rely on the legacy modules (`MBEDTLS_[CCM|GCM|CHACHAPOLY]`)
+with the following conditions on the underlying key types:
+- CCM/GCM can either use legacy key type modules `MBEDTLS_[AES|ARIA|CAMELLIA]_C`
+ or their accelerated version, as described in section
+ ["Partial acceleration for CCM/GCM"](#partial-acceleration-for-CCM/GCM).
+- ChaChaPoly instead can only rely on legacy key type module `MBEDTLS_CHACHA20_C`
+ and algorithm `MBEDTLS_POLY1305_C`.
It should be noticed that disabling `MBEDTLS_CIPHER_C` helps in reducing code's
footprint, but unfortunately it makes the following modules unavailable: