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The RX DMA descriptors(MAC/DMA)

sunyuanling1022
Associate II
Posted on March 19, 2007 at 00:19

The RX DMA descriptors(MAC/DMA)

1 REPLY 1
sunyuanling1022
Associate II
Posted on May 17, 2011 at 09:39

Hi veryone!Before you start the RX DMA,you should have to allocate a 16-byte region in main memmory,for each DMA transfer.3 words for DMA descriptors,plus 1 word for Packet Status and descriptor VALID bit.In the first three descritor words ,you write the information to be loaded in the : ENET_RXCR,ENET_RXSAR,ENET_RXNDAR.

Do these mean that: when I use the follow codes to init the descritor,it is equal to write the data to the accordingly register directly?

dmaRxDscrBase.dmaAddr = (u32)RxBuff;

/* Initialize RX ENET Status and control */

dmaRxDscrBase.dmaStatCntl = 0x0;

/* Initialize the next descriptor- In our case its single descriptor */

dmaRxDscrBase.dmaNext = (u32)pRXDescrChain;

Best regards!

sunshan