Messages in this thread | | | Date | Wed, 8 Sep 2021 17:49:17 -0700 | Subject | Re: Circular dependency between DSA switch driver and tagging protocol driver | From | Florian Fainelli <> |
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On 9/8/2021 5:26 PM, Vladimir Oltean wrote: > On Wed, Sep 08, 2021 at 03:14:51PM -0700, Florian Fainelli wrote: >>> Where is the problem? >> >> I'd say with 994d2cbb08ca, since the tagger now requires visibility into >> sja1105_switch_ops which is not great, to say the least. You could solve >> this by: >> >> - splitting up the sja1150 between a library that contains >> sja1105_switch_ops and does not contain the driver registration code > > I've posted patches which more or less cheat the dependency by creating > a third module, as you suggest. The tagging protocol still depends on > the main module, now sans the call to dsa_register_switch, that is > provided by the third driver, sja1105_probe.ko, which as the name > suggests probes the hardware. The sja1105_probe.ko also depends on > sja1105.ko, so the insmod order needs to be: > > insmod sja1105.ko > insmod tag_sja1105.ko > insmod sja1105_probe.ko > > I am not really convinced that this change contributes to the overall > code organization and structure.
Yes, I don't really like it either, maybe we do need to resolve the other dependency created with 566b18c8b752 with a function pointer/indirect call that gets resolved at run-time, assuming the overhead is acceptable.
> >> - finding a different way to do a dsa_switch_ops pointer comparison, by >> e.g.: maintaining a boolean in dsa_port that tracks whether a particular >> driver is backing that port > > Maybe I just don't see how this would scale. So to clarify, are you > suggesting to add a struct dsa_port :: bool is_sja1105, which the > sja1105 driver would set to true in sja1105_setup?
Not necessarily something that is sja1105 specific, but something that indicates whether the tagger is operating with its intended switch driver, or with a "foreign" switch driver (say: dsa_loop for instance).
> > If this was not a driver I would be maintaining, just watching as a > reviewer, I believe "no" is what I would say to that. >
-- Florian
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