Apple has released iOS 5.1.1 firmware for iPhone, iPad and iPod Touch.Though it is being advised that Jailbreakers should stay away from updating to iOS 5.1.1, but if you have updated to iOS 5.1.1 then you can downgrade to iOS 5.0.1 or previous versions.
iJailbreak has come up with a guide to downgrade iPhone 4S/4/3GS, iPad 3/2/1 and iPod Touch 4G/3G to iOS 5.0.1 or iOS 5.0 firmware from iOS 5.1.1 with the help of iFaith.
To downgrade iOS 5.1.1 to iOS 5.1 or previous versions you require a Windows computer,APTicket and Saved SHSH blobs for iOS 5.1, 5.0.1 or previous firmware.The tutorial is ONLY for A4 devices.
How to downgrade from iOS 5.1.1 to iOS 5.0.1,iOS 5.0
1. In the first step download iFaith by iH8Sn0w.
Also Read: Save SHSH Blobs With iFaith (How To)
2. Run iFaith and then click on “OK” button after reading the warning message.
3. Now, click on Select “Build IPSW with Blob”.
4. Browse and select the SHSH blobs for the iOS 5.0.1 or iOS 5.0 firmware.
5. Browse and select the iOS 5.0.1 or iOS 5.0 firmware to which you want to downgrade.
6. iFaith will create a custom firmware file for you.
7. Now, go back to the Main Menu of iFaith and click the Use DFU Pwner (iREB) button.Follow the on-screen instructions to put your idevice into into Pwned DFU Mode.
8. While your device is in Pwned DFU Mode,open iTunes and restore your device to the custom firmware file you created.
Your device is now downgraded to iOS 5.0.1 or iOS 5.0 from iOS 5.1.1.