Hi, Andrew On 2017/6/29 21:56, Andrew Lunn wrote: >>> You only call dev_close() if the device is running. What if somebody >>> runs the self test on an interface when it has never been opened? It >>> looks like you will call phy_resume(). But since it has never been >>> suspended, you could be in trouble. >> Here is what I can think of: >> 1. when the mac driver is first loaded, the phy has a default state. >> suspended? > > Nope. The PHY will only be suspended when you actually call > phy_suspend. > >> 2. If user runs the self test after using 'ifconfig ethX down', then I >> suppose >> phy is already suspended. > > Assuming the phy has at some point been up, after a down, it should be > suspended. > > The key thing here is, phy_resume() can only be called after a > successful phy_suspend(). Those are the power management rules, and > the expectations of the drivers. Doing a resume without first doing an > explicit suspend is asking for bad things to happen. > > You are having trouble because you are not using the API for what it > was intended. Maybe you need to take a step back and look at the > bigger picture of how self tests are being performed. Why do you need > the dev_close()/dev_open()? Maybe > netif_device_detach()/netif_device_attach() would be better? > How do other drivers do self test? > Basically, when doing a loopback test, we put a skb in the tx ring, and see if we can receive it in the rx ring. And We can't find other functions that meets our requirement, except dev_close()/dev_open.
netif_device_detach only stop the stack from sending packet, napi_disable is needed to stop the stack from receiving packet. And after phy loopback test, netif_device_attach does not bring back the link. Is there a way to bring back the link? We still need to resume the phy after 'ifconfig ethX down'. Also how can I tell the difference between phy being suspended after 'ifconfig ethX down' and phy being not suspended after mac driver is first loaded? It seems that ixgbe_ethtool in mainline kernel also use netif_tx_disable, napi_disable and other hardware specific method to setup self test. But newest ixgbe_ethtool code in github also use dev_close to do self test. Any idea? Best Regard Yunsheng Lin
