linux内核驱动dm9000aep老是link up ,link down

我用2440芯片，裸机程序和uboot驱动dm9000aep没问题（但片选上必须加电容才行，不知道为什么），但linux内核驱动就老是这样
eth0: link down
eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
eth0: link down
eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
eth0: link down
eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
eth0: link down
eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
dm9000 dm9000.0: status check fail: 6
eth0: link down
eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
谁知道这是为什么呀，是片选，读写信号的问题吗，需要加电容马

dm9000 dm9000.0: entering dm9000_interrupt
dm9000 dm9000.0: interrupt status 20
dm9000 dm9000.0: phy_read[01] -> 7849
dm9000 dm9000.0: entering dm9000_interrupt
dm9000 dm9000.0: interrupt status 20
dm9000 dm9000.0: entering dm9000_interrupt
dm9000 dm9000.0: interrupt status 20
dm9000 dm9000.0: phy_read[01] -> 784d
dm9000 dm9000.0: phy_read[04] -> 01e1
dm9000 dm9000.0: phy_read[05] -> 41e1
eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
dm9000 dm9000.0: phy_read[01] -> 7849
dm9000 dm9000.0: phy_read[01] -> 784d
dm9000 dm9000.0: entering dm9000_interrupt
dm9000 dm9000.0: interrupt status 20
dm9000 dm9000.0: entering dm9000_interrupt
dm9000 dm9000.0: interrupt status 20
dm9000 dm9000.0: phy_read[01] -> 7849
dm9000 dm9000.0: phy_read[01] -> 784d
dm9000 dm9000.0: entering dm9000_interrupt
dm9000 dm9000.0: interrupt status 20
调试发现老是entering dm9000_interrupt
进2次是怎么回事？