OK, it is a week later and as promised we will have a few words about the issues we are facing.
The system requirements have been defined by a customer for the MPC5200B based EFIKA.
The system needs to support concurrent operation with random load on the following peripherals:
a) PCI bus master (video MPEG decoding engine/GFX)
b) onchip USB
c) onchip Ethernet
d) onchip ATA
e) onchip sound (AC97)
The sound is the only real-time device on this list, as drops in sound are instantly recognizable by the application (user). This needs the AC97 bestcom task to run at the highest priority.
USB and PCI DMA have NOT shown an impact on this requirement so far.
Ethernet is fail-safe by protocol implementation => therefore this can run at a low priority.
ATA has been shown to be the main challenge, as the UDMA statemachine does not take care of the FIFO filling. We are focused on this. The workaround we are crafting is a bestcomm driven PIO driver -- the drive is setup for PIO operation, but the data is copied from/to the drive using a bestcomm task to offload this from the PPC core. This should solve the targeted average disk performance of 6Mb/s which would cover the systems requirements given to us by our main customer. As soon as we confirm we have this done, we will release the board.
So mote it be!
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