08/01/2020 13:59, Ferruh Yigit: > On 1/8/2020 10:31 AM, Laurent Hardy wrote: > > Hi all, > > > > On 1/8/20 10:55 AM, David Marchand wrote: > >> On Wed, Jan 8, 2020 at 10:09 AM Ferruh Yigit <ferruh.yi...@intel.com> > >> wrote: > >>> On 1/8/2020 8:56 AM, David Marchand wrote: > >>>> Hello Laurent, > >>>> > >>>> Bonne année. > >>>> > >>>> Cc: maintainers. > >>>> > >>>> On Tue, Jan 7, 2020 at 3:57 PM Laurent Hardy <laurent.ha...@6wind.com> > >>>> wrote: > >>>>> In current led control API we have no way to know if a device is able > >>>>> to handle on/off requests coming from the application. > >>>>> Knowing if the device is led control capable could be useful to avoid > >>>>> exchanges between application and kernel. > >>>>> Using the on/off requests to flag if the device is led control capable > >>>>> (based on the ENOSUP returned error) is not convenient as such request > >>>>> can change the led state on device. > >>>>> > >>>>> This patch adds a new function rte_eth_led_ctrl_capable() that will look > >>>>> for led_off/on dev ops availability on the related pmd, to know if the > >>>>> device is able to handle such led control requests (on/off). > >>>> This patch breaks the ABI, which is BAD :-). > >>> Why it is an ABI break, dev_ops should be between library and drivers, so > >>> it > >>> should be out of the ABI concern, isn't it. > >> You are right. > >> So in our context, this is not an ABI breakage. > >> But abidiff still reports it, so maybe some filtering is required to > >> avoid this false positive. > >> > >> Note that if we insert an ops before rx_queue_count, we would have a > >> real ABI breakage, as this ops is accessed via an inline wrapper by > >> applications. > >> > >> > >>>> This new api only needs to look at the existing ops, so you can remove > >>>> the (unused in your patch) dev_led_ctrl_capable ops. > >>>> > >>>> OTOH, would it make sense to expose this capability in dev_flags? > >>>> > >>> 'rte_eth_led_on()' & 'rte_eth_led_off()' APIs returns '-ENOTSUP' when the > >>> not > >>> supported, can that help application to understand? > >> You might want to know it is supported without changing the state. > >> Laurent? > > > > First, happy new year :) > > > > Yes exactly, the purpose of this patch is to query if the device is led > > control capable or not without changing the led state. > > > > About exposing the capability through a dev_flags, means to make some > > modification in each pmds. It looks more easy in term of pmds > > maintenance to relying on the rte_eth_led_off()/on() dev ops > > availability at rte_ethdev level, right ? > > > > 'dev_flag' definition is not clear, right now it holds the combination of > status > and capability. And we have 'rte_eth_dev_info' struct, which is again > combination of device capability and status.
I agree capabilities in ethdev are a bit of a mess. I would appreciate someone makes a complete audit of it so we can discuss how to improve the situation. > Perhaps we should have explicit capabilities and status fields, even in the > rte_device level which inherited by net/crypto devices etc.. No, ethdev capabilities should stay in ethdev. > But for dev_ops, instead of having another capabilities indicator, which > requires PMDs to keep this synchronized, I think it is better if we can self > contain this information within dev_ops, like not implementing dev_ops would > mean it is not supported, this way it is easier to maintain and less error > prone. It means the dev_ops is resetted at init if a device does not support the feature. It is against having const dev_ops. > Only we should have it without side effect, > > 1- adding an additional 'dry-run' parameter can work, but this means breaking > ABI and updating majority of the ethdev APIs :) > 2- Adding 'is_supported' versions of the APIs as we need can be an option, > like > 'rte_eth_led_on_is_supported()' > 3- Olivier's suggestion to add a new API to get the led status, so that this > information can be used select led API which won't cause side affect and let > us > learn if it is supported. > > Any other alternatives? > > I would prefer the 2) in above ones, which is very similar to the original > patch. The other alternatives are in rte_eth_dev_info and dev_flags.
