Keyboard detected by not working in BIOS
We have board with Intel Atom processor and Phoenix Award BIOS.
1) When keyboard alone is connected to the board at the startup,the keyboard is detected by BIOS (because it is not showing keyboard error) but either of the two conditions given below happens every time.
a) BIOS is not entering BIOS menu when DEL key is pressed.
b) BIOS enters BIOS menu but,once it enters none of the key press is detected.
Pls note that without keyboard detection,neither BIOS menu will be reached nor the BIOS continues without keyboard error.So in either of the above cases keyborad detection happens.
2) When keyboard along with mouse is connected to the board,there is no problem at all.
3) When 2 keyboards are connected,problem stated in (1) persists.
4) When keyboard is not connected at startup,BIOS shows keyboard error.Now if we connect the keyboard,everything works fine.
5) In bootloader and OS,keyboard works fine.
6) USB analyser was connected to view the transactions happening when board is in condition 1(b).All the key press are received and acknowledged by the processor.ie.No error is identified.The USB enumeration is proper.Similarly the IN,DATA0,DATA1 and ACK packets are proper.
7)Different keyboards were tried.Result is the same.
What could be the reason for this?