SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The TPCC is the EDMA transfer scheduler responsible for scheduling, arbitrating, and issuing user programmed transfers to the two TPTCs.
Figure 16-16 shows a functional block diagram of the EDMA channel controller (EDMA_TPCC).
The main blocks of the EDMA_TPCC are as follows:
Other functions include the following:
The EDMA_TPCC includes two channel types: DMA channels (64 channels) and QDMA channels (8 channels).
Each channel is associated with a given event queue/transfer controller and with a given PaRAM set. The main difference between a DMA channel and a QDMA channel is the method that the system uses to trigger transfers.
Figure 16-16 is a block diagram of the EDMA_TPCC.
The EDMA_TPCC supports up to 64 DMA channels and up to 8 QDMA channels. These channels are identical, except for how they are triggered:
DMA events are always higher priority than QDMA events. The higher-priority event is placed in the event queue to await submission to the transfer controllers, which occurs at the earliest opportunity. Each event queue is serviced in FIFO order, with a maximum of 16 queued events per event queue. If more than one TPTC is ready to be programmed with a transmission request (TR), the event queues are serviced with fixed priority: Q0 is higher than Q1. When an event is ready to be queued and the event queue and the TC channel are empty, the event bypasses the event queue and goes directly to the PaRAM processing logic for submission to the appropriate TC. If the transfer request TR bus or PaRAM processing are busy, the bypass path is not used. The bypass is not used to dequeue for a higher-priority event.
Events are extracted from the event queue when the EDMA_TPTC is available for a new TR to be programmed into the EDMA_TPTC (signaled with the empty signal, indicating an empty program register set). As an event is extracted from the event queue, the associated PaRAM entry is processed and submitted to the TPTC as a TR. The TPCC updates the appropriate counts and addresses in the PaRAM entry in anticipation of the next trigger event for that PaRAM entry.
The EDMA_TPCC also has an error detection logic that causes an error interrupt generation on various error conditions (for example: missed events EDMA_TPCC_EMR and EDMA_TPCC_EMRH registers, exceeding event queue thresholds in EDMA_TPCC_CCERR register, etc.).