Now that version 2.2.9 and newer firmware is signed firmware (all earlier versions are unsigned), all upgrades and downgrades are performed using the 2.2.7-2 pkg files that are available from My Oracle Support (https://support.oracle.com) patch ID 26575824.
You can downgrade from firmware 2.2.7 to 2.1.8 or 2.1.7. You downgrade to firmware 2.1.8 using a special downgrade version of firmware 2.1.8. After this is done, you can then downgrade from firmware 2.1.8 to 2.1.6. The special downgrade version of the 2.1.8 firmware is part of patch 22173626 available at My Oracle Support. Ensure that you read the README file included in the patch.
You can downgrade from firmware 2.2.7 to 2.1.6 if your management controller is of the older type. See Determine Management Controller Type. You downgrade to firmware 2.1.6 using a special downgrade version of firmware 2.1.6. After this is done, you can then downgrade from firmware 2.1.7 to any supported firmware. See Upgrade and Downgrade Paths Supported. The special downgrade version of the 2.1.7 firmware is part of patch 20380281 available at My Oracle Support. Ensure that you read the README file included in the patch.
Newer management controllers cannot be downgraded to 2.1.7 or lower. To determine if your management controller is the newer type, see Determine Management Controller Type.
When upgrading or downgrading between 2.1.x and 2.2.2-2.2.7, the initial firmware upgrade or downgrade might display an error at the beginning and then exit. This is normal. An installer in the firmware has set or reset prerequisite values. Repeat the upgrade or downgrade.
For greater security, ensure that all Sun Network QDR InfiniBand Gateway Switches and Sun Datacenter InfiniBand Switch 36 switches are upgraded to the latest firmware version. A miss-match of firmware versions reduces or negates secret M_Key functionality, and compromises fabric security.
For example, in a mixed 2.2.7 and 2.1.5 fabric, where SMs are running on both 2.2.7and 2.1.5 switches, you must use the –override-inconsistent-partition-configurations option with the smsubnetprotection command. To do this is insecure.