Re: rate control vs. bands

[Johannes Berg <johannes@sipsolutions.net>]

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> During my rate control work I noticed that the band handling there is
> somewhat awkward, and I wanted to collect opinions.
> 
> Currently, much of the code assumes that neither we nor station in our
> bSS change bands; the PID algorithm even says:
> 
>         /* We can safely assume that sband won't change unless we get
>          * reinitialized. */
> 
> which doesn't really seem true.

I haven't checked so far, but I think you can make it switch:
 * bring up two IBSS interfaces in 2.4 GHz, have them sync
 * switch the leader to a channel in 5 GHz
 * the follower will hopefully find the leader and switch there, but the
   sta_info for the follower will, on the leader, still have sband 2GHz

> For the rate control algorithms, I was just thinking about removing the
> rate_init() callback because this can just as well be done when
> allocating the station. However, currently we don't pass the band to the
> alloc_sta function, so that isn't possible right now.

So it seems that this sucks for rate control algorithms; we need to make
sure rate_init is always called during alloc_sta initially (so we don't
forget like mesh does right now! nbd, make sure to test mesh and
possibly fix it please.)

We also need to investigate calling rate_init again when the sta has
switched band for some reason.

johannes

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