On Tue, Jun 21, 2016 at 08:24:36AM +0000, Lu, Wenzhuo wrote: > Hi Jerin,
Hi Wenzhuo, > > > > > > On Mon, Jun 20, 2016 at 02:24:27PM +0800, Wenzhuo Lu wrote: > > > > > > > Add an API to reset the device. > > > > > > > It's for VF device in this scenario, kernel PF + DPDK VF. > > > > > > > When the PF port down->up, APP should call this API to reset > > > > > > > VF port. Most likely, APP should call it in its management > > > > > > > thread and guarantee the thread safe. It means APP should stop > > > > > > > the rx/tx and the device, then reset the device, then recover > > > > > > > the device and rx/tx. > > > > > > > > > > > > Following is _a_ use-case for Device reset. But may be not be > > > > > > _the_ use case. IMO, We need to first say expected behavior of > > > > > > this API and add a use-case later. > > > > > > > > > > > > Other use-case would be, PCIe VF with functional level reset for > > > > > > SRIOV migration. > > > > > > Are we on same page? > > > > > > > > > > > > > > > In my experience with Linux devices, this is normally handled by > > > > > the device driver in the start routine. Since any use case which > > > > > needs this is going to do a stop/reset/start sequence, why not > > > > > just have the VF device driver do this in the start routine?. > > > > > > > > > > Adding yet another API and state transistion if not necessary > > > > > increases the complexity and required test cases for all devices. > > > > > > > > I agree with Stephen here.I think if application needs to call start > > > > after the device reset then we could add this logic in start itself > > > > rather exposing a yet another API > > > Do you mean changing the device_start to include all these actions, stop > > device -> stop queue -> re-setup queue -> start queue -> start device ? > > > > What was the expected API call sequence when you were introduced this API? > > > > Point was to have implicit device reset in the API call sequence(Wherever > > make > > sense for specific PMD) > I think the API call sequence depends on the implementation of the APP. Let's > say if there's not this reset API, APP can use this API call sequence to > handle the PF link down/up event, rte_eth_dev_close -> rte_eth_rx_queue_setup > -> rte_eth_tx_queue_setup -> rte_eth_dev_start. > Actually our purpose is to use this reset API instead of the API call > sequence. You can see the reset API is not necessary. The benefit is to save > the code for APP. Then I am bit confused with original commit log description. | |It means APP should stop the rx/tx and the device, then reset the |device, then recover the device and rx/tx. | I was under impression that it a low level reset API for this device? Is n't it? The other issue is generalized outlook of the API, Certain PMD will not have PF link down/up event? Link down/up and only connected to VF and PF only for configuration. How about fixing it more transparently in PMD driver itself as PMD driver knows the PF link up/down event, Is it possible to recover the VF on that event if its only matter of resetting it? Jerin
