SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
An Tx channel teardown is initiated by the host by writing the TX_TEARDOWN bit in the Tx Channel N Realtime Control Register. When the host initiates teardown, it can choose to perform either a graceful (no data loss) or forced teardown of the channel depending on the setting of the TX_FORCED_TEARDOWN bit in the Tx Channel N Realtime Control Register.
If the TX_FORCED_TEARDOWN bit is clear, a normal teardown has been initiated. In this case, the UDMA will do the following:
Bits | Field | Value | Description |
---|---|---|---|
31 | Forced | 0 | Indicates that the teardown was graceful and data was not lost. |
30:14 | - | 0 | RESERVED |
13:4 | Channel ID | channel number | Indicates which channel the teardown completed on |
3:0 | Teardown Indicator | 0x1 | Indicates that a teardown has completed – normal pointers must be 16 byte aligned so this value indicates this is a teardown |
If the TX_FORCED_TEARDOWN bit is set, a destructive teardown has been initiated. In this case, the UDMA will do the following:
Bits | Field | Value | Description |
---|---|---|---|
31 | Forced | 1 | Indicates that the teardown was not graceful. Data was potentially lost. |
30:14 | - | 0 | RESERVED |
13:4 | Channel ID | channel number | Indicates which channel the teardown completed on |
3:0 | Teardown Indicator | 0x1 | Indicates that a teardown has completed – normal pointers must be 16 byte aligned so this value indicates this is a teardown |
The host may issue a teardown on any channel at any time, regardless of whether the channel is actively receiving a packet or not.
The host determines that a teardown is complete by periodically polling the teardown and enable bits for the channel or by waiting to receive the teardown record on the queue specified in the Tx Channel Completion Queue register for the channel.