On Thu, 21 May 2020 09:18:44 +0000 Mark Starovoytov wrote: > Hi Jakub, > > > > In the first generation of our hardware (A1), a whole traffic class is > > > consumed for PTP handling in FW (FW uses it to send the ptp data and > > > to send back timestamps). > > > Since this conflicts with QoS (user is unable to use the reserved > > > TC2), we suggest using module param to give the user a choice: > > > disabling PTP allows using all available TCs. > > > > Is there really no way to get the config automatically chosen when user sets > > up TCs or does SIOCSHWTSTAMP? It's fine to return -EOPNOTSUPP when too > > many things are enabled, but user having to set module parameters upfront > > is quite painful. > > Module param is not a must have for usage, default config allows the > user to use TCs and PTP features simultaneously with one major > limitation: TC2 is reserved for PTP, so if the user tries to > send/receive anything on TC2, if won't quite work unfortunately. If > the user wants to get "everything" from QoS/TC (e.g. use all the TCs) > - he can explicitly disable the PTP via module param. > > Right now we really aren't sure we can dynamically rearrange > resources between QoS and PTP, since disabling/enabling PTP requires > a complete HW reconfiguration unfortunately. Even more unfortunate is > the fact that we can't change the TC, which is reserved for PTP, > because TC2 is hardcoded in firmware. > > We would prefer to keep things as is for now, if possible. We'll > discuss this with HW/FW team(s) and submit a follow-up patch, if we > find a way to automatically choose the config.
Module parameters are very strongly discouraged for networking drivers. They also constitute uAPI, and can't be changed, short-term solution like that is really far from ideal.
