2.2 BSP Rel. 1.0 for PPMC-275 Programmer's Guide

API Call Reference List of APIs
SDMA_STATUS sdmaRxReturnBuff(SDMA_CHANNEL *sdmaChan, PKT_INFO *pPktInfo)
DESCRIPTION This routine returns a Rx buffer back to the Rx ring. It retrieves the
next 'used' descriptor and attached the returned buffer to it. In case
the Rx queue was in "resource error" condition, where there are no
available Rx resources, the function resets the resource error flag.
INPUT
SDMA_CHANNEL
*sdmaChan
PKT_INFO
*pPktInfo
SDMA channel struct pointer
Packet struct pointer.
OUTPUT New available Rx resource in Rx descriptor ring.
RETURN
Driver Introduction
Software Modules
SDMA_ERROR In case the routine can not access Rx desc ring.
SDMA_OK Otherwise.
This module allocates the descriptors for each MPSC and each
Ethernet port (separate chain for each priority) depending on the
protocol programmed for this port. The descriptors allocating
method defines the minimum and maximum number of descriptors
per port protocol. Each protocol allows a limited number of
descriptors to avoid one port consuming all the resources. Each
descriptor chain allocation results in the addition of the chain's
first pointer to a table of pointers that is used by the Low Level
Driver to initialize the DMA.
Tx descriptors are allocated for each port (four Tx DMA exist) with
Buffer Pointer NULL.
This driver is implemented in:
• sdma.c
VxWorks 5.5/Tornado 2.2 BSP Rel. 1.0 for PPMC-275 5 - 65