08/01/2020 15:15, Andrew Rybchenko: > On 1/8/20 4:52 PM, Ferruh Yigit wrote: > > On 1/8/2020 1:25 PM, Thomas Monjalon wrote: > >> 08/01/2020 14:20, Ferruh Yigit: > >>> On 1/8/2020 1:06 PM, Thomas Monjalon wrote: > >>>> 08/01/2020 13:59, Ferruh Yigit: > >>>>> 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. > >>> > >>> I didn't get your comment. > >>> For example getting FW version, I am saying instead of keeping another > >>> piece of > >>> information to say if it is supported by device/driver, better to grasp > >>> this > >>> from if the driver implemented 'fw_version_get' dev_ops or not. > >> > >> I like this approach. > >> Capabilities should be expressed by setting the function pointer or not > >> (NULL). > >> But a driver may support a feature for a subset of devices. > > > > In that case dev_ops itself can return the '-ENOTSUP', since application > > interaction will be through the ethdev API, either API send '-ENOTSUP' > > because > > the dev_ops is NULL or dev_ops itself send the '-ENOTSUP' because of the > > underlying version of the device, for application it will be clear that that > > feature is not supported. > > I think it is a good illustration why deriving the capability > from dev_ops pointer is not that good idea. > > >> If a device does not support a feature, the function pointer must be set > >> to NULL. > >> The only issue is having dev_ops as a const struct. > > > > Not sure about changing the dev_ops on runtime, it can be very hard to > > debug. > > I hope it was just an idea to copy dev_ops and adjust in > accordance with the device capabilities on register. > I.e. not fully dynamic changes in runtime.
Changing a function pointer in runtime is tough :) I was thinking about changing it during init but I don't really see a great value. Probably better to return ENOTSUP. Anyway it does not address the capability info need.
