关于e1000_configure_tx的疑问。。。

chishanmingshen

/**
* e1000_configure_tx - Configure 8254x Transmit Unit after Reset
* @adapter: board private structure
*
* Configure the Tx unit of the MAC after a reset.
**/

static void e1000_configure_tx(struct e1000_adapter *adapter)
{
        u64 tdba;
        struct e1000_hw *hw = &adapter->hw;
        u32 tdlen, tctl, tipg;
        u32 ipgr1, ipgr2;

        /* Setup the HW Tx Head and Tail descriptor pointers */

        switch (adapter->num_tx_queues) {
        case 1:
        default:
                tdba = adapter->tx_ring[0].dma;
                tdlen = adapter->tx_ring[0].count *
                        sizeof(struct e1000_tx_desc);
                ew32(TDLEN, tdlen);
                ew32(TDBAH, (tdba >> 32));
                ew32(TDBAL, (tdba & 0x00000000ffffffffULL));

                ew32(TDT, 0);
                ew32(TDH, 0);
                adapter->tx_ring[0].tdh = ((hw->mac_type >= e1000_82543) ? E1000_TDH : E1000_82542_TDH);
                adapter->tx_ring[0].tdt = ((hw->mac_type >= e1000_82543) ? E1000_TDT : E1000_82542_TDT);
                break;
        }

}

TDT/TDH寄存器和tdt/tdh字段到底是什么含义？请指点，谢谢！

chishanmingshen

刚看明白了：TDH和TDT之间是网卡接着需要处理的空间，next_to_clean和TDH是网卡已经处理完的空间。

TDH:
This register contains the head pointer for the transmit descriptor ring. It holds a value that is an
offset from the base, and indicates the in–progress descriptor.

TDT:
This register contains the tail pointer for the transmit descriptor ring. It holds a value that is an
offset from the base, and indicates the location beyond the last descriptor hardware can process.

chishanmingshen

还是有点不明白，这些寄存器应该是基于ring的啊，怎么看代码好像是基于adapter的？

求助，谢谢！

chishanmingshen

自己搞明白了，e1000就一个ring！无所谓基于adapter和ring了。

结贴！