Samsung S5PC110 Manual page 1876

S5PC110_UM
4.3.3 OPERATION FLOW CHART
When you initialize the AC97 controller, you must assert system reset or cold reset, because the previous state of
the external AC97 audio-codec is not known. This assures that GPIO is already ready. Then you enable the codec
ready interrupt. You can check codec ready interrupt by polling or interrupt. When interrupt occurs, you must de-
assert codec ready interrupt. Use DMA or PIO (directly to write data to register) to transmit data from memory to
register or from register to memory. If internal FIFOs (TX FIFO or RX FIFO) are not empty, then let data be
transmitted.
Time out condition ?
Controller off
No
Yes
Figure 4-3
System reset or Cold reset
Set GPIO and Release
INTMSK/SUBINTMSK bits
Enable Codec Ready interrupt
No
Codec Ready interrupt ?
Disable Codec Ready interrupt
DMA operation or
PIO (Interrupt or Polling ) operation
AC97 Operation Flow Chart
4 AC97 CONTROLLER
4-4