> -----Original Message----- > From: Jerin Jacob [mailto:jerin.jacob at caviumnetworks.com] > Sent: Wednesday, June 22, 2016 12:15 PM > To: Lu, Wenzhuo > Cc: Ananyev, Konstantin; Stephen Hemminger; dev at dpdk.org; Richardson, > Bruce; Chen, Jing D; Liang, Cunming; Wu, Jingjing; Zhang, Helin; > thomas.monjalon at 6wind.com > Subject: Re: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support device reset > > On Wed, Jun 22, 2016 at 03:32:16AM +0000, Lu, Wenzhuo wrote: > > Hi Jerin, > > > > > -----Original Message----- > > > From: Jerin Jacob [mailto:jerin.jacob at caviumnetworks.com] > > > Sent: Wednesday, June 22, 2016 10:38 AM > > > To: Lu, Wenzhuo > > > Cc: Ananyev, Konstantin; Stephen Hemminger; dev at dpdk.org; > > > Richardson, Bruce; Chen, Jing D; Liang, Cunming; Wu, Jingjing; > > > Zhang, Helin; thomas.monjalon at 6wind.com > > > Subject: Re: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support > > > device reset > > > > > > On Wed, Jun 22, 2016 at 01:35:37AM +0000, Lu, Wenzhuo wrote: > > > > Hi Jerin, > > > > > > > > > -----Original Message----- > > > > > From: Jerin Jacob [mailto:jerin.jacob at caviumnetworks.com] > > > > > Sent: Tuesday, June 21, 2016 10:29 PM > > > > > To: Ananyev, Konstantin > > > > > Cc: Lu, Wenzhuo; Stephen Hemminger; dev at dpdk.org; Richardson, > > > > > Bruce; Chen, Jing D; Liang, Cunming; Wu, Jingjing; Zhang, Helin; > > > > > thomas.monjalon at 6wind.com > > > > > Subject: Re: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support > > > > > device reset > > > > > > > > > > On Tue, Jun 21, 2016 at 02:03:15PM +0000, Ananyev, Konstantin wrote: > > > > > > > > > > > > > > > > > > > > > > > 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? > > > > > > > > > > > > > > > > > > > > I think we already went through that discussion on the list. > > > > > > > > > > Unfortunately with current dpdk design it is hardly > > > > > > > > > > possible. > > > > > > > > > > To achieve that we need to introduce some sort of > > > > > > > > > > synchronisation between IO and control APIs (locking or so). > > > > > > > > > > Actually I am not sure why having a special reset > > > > > > > > > > function will be a > > > > > problem. > > > > > > > > > > > > > > > > > > | > > > > > > > > > |It means APP should stop the rx/tx and the device, then > > > > > > > > > |reset the device, then recover the device and rx/tx. > > > > > > > > > | > > > > > > > > > Just to understand, If application still need to do the > > > > > > > > > stop then what value addtion reset API brings on the table? > > > > > > > > > > > > > > > > If application calls dev_reset() it doesn't need to call > > > > > > > > dev_stop() before > > > it. > > > > > > > > dev_reset() will take care of it. > > > > > > > > But it needs to make sure that no other thread will try to > > > > > > > > modify that device state (either dev_stop/start, or > > > > > > > > eth_rx_busrst/eth_tx_burst) > > > > > while the reset op is in place. > > > > > > > > > > > > > > OK. This description looks different than commit log and API > > > > > > > doxygen > > > > > comment. Please fix it. > > > > > > > How about a different name for this API. Device reset is too > > > > > > > generic? > > > > Any suggestion? I use this name because I believe what this API do > > > > is to reset > > > the device. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Yes, it would exist only for VFs, for PF it could be > > > > > > > > > > left > > > unimplemented. > > > > > > > > > > Though it definitely seems more convenient from user > > > > > > > > > > point of view, they would know: to handle VF reset > > > > > > > > > > event, they just need to call that particular > > > > > > > > > > function, not to re-implement their > > > own. > > > > > > > > > What if driver returns "not implemented" then > > > > > > > > >application will have do generic > rte_eth_dev_stop/rte_eth_dev_start. > > > > > > > > >That way in application perspective we are NOT solving any > problem. > > > > > > > > > > > > > > > > True, but as I said for PF application would just never receive > > > > > > > > such > event. > > > > > > > What is this event ? Is it VF Link up/down event? > > > > > > > > > > > > > > No I was referring to VF itself, Other VF PMD drivers in > > > > > > > drivers/net where this callback is not implemented. > > > > > > > > > > > > Hmm, the only suggestion I have here - Maintainers/developers > > > > > > of non-Intel PMD will implement it for their VFs? > > > > > > > > > > That's fine. But, We have to know what to implement here in PMD > > > perspective? > > > > > That's reason being asking about the API expectation and > > > > > application usage :-) > > > > > > > > > > > In case of course they do need to handle similar event. > > > > > Which is this event and How application get notify it. > > > > When the PF link is down/up, the PF will use the mailbox to send a > > > > message to > > > VF. The event here means the VF receives that message from PF. So VF > > > can know the physical link state changed. You see it's only for VF. > > > PF will not receive such kind of message. > > > > And we use the callback mechanism to let APP notified. APP should > > > > register a > > > callback function. When VF driver receives the message it will call > > > the callback function, then APP can know that. > > > > > > How about the standardizing a name for that event like > > > RTE_ETH_EVENT_INTR_DOWNSTREAM_LSC or > RTE_ETH_EVENT_INTR_PF_LSC or > > > similar (like RTE_ETH_EVENT_INTR_RESET) and counter API in VF to > > > handle the specific event whose API name similar to selected event > > > name not eth_dev_reset(reset sounds like more like HW reset, In PCIe > > > device perspective FLR etc) > > > > > > OR > > > > > > How about handling in more generic way where a generic alert message > > > send by PF to VF like RTE_ETH_EVENT_INTR_PF_ALERT or similar. > > > And have only one handle functions in VF side so that in future we > > > can keep adding new functionality with out introducing new counter > > > API in VF > > > > > > Jerin > > Lost here. I think these RTE_ETH_EVENTs are used to connect the APP call > back functions with the events. > > Actually I want the APP to register a callback function > > reset_event_callback for > the reset event. Like this, > > /* register reset interrupt callback */ > > rte_eth_dev_callback_register(portid, > > RTE_ETH_EVENT_INTR_RESET, reset_event_callback, > NULL); And when the > > VF driver finds PF link down/up, it should use > _rte_eth_dev_callback_process(dev, RTE_ETH_EVENT_INTR_RESET) to run into > the callback which is provided by APP. Means reset_event_callback here. > > me too. Their is existing RTE_ETH_EVENT_INTR_RESET event to notify the PF > reset.I guess it is not for the PF link change or it isfor generic VF reset > request > initiated by PF for everything. I think this event is for device reset not only for PF but also can for VF. I think we can use this event when the driver want the APP to reset the device. The PF link down/up caused VF reset is one of the cases.
> > file: lib/librte_ether/rte_ethdev.h > RTE_ETH_EVENT_INTR_RESET, > /**< reset interrupt event, sent to VF on PF reset */ > ^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > if application need to call rte_ethdev_reset() on RTE_ETH_EVENT_INTR_RESET > event then please mention it commit log or API description. Good suggestion. I'll try to find where's the good place to add more explanation. >
