Re: [Rt2400-devel] Mode selection in mac80211

[Ivo van Doorn <ivdoorn@gmail.com>]

On Tuesday 09 October 2007, Johannes Berg wrote:
> On Tue, 2007-10-09 at 19:54 +0200, Ivo van Doorn wrote:
> 
> > > Well, it's not too strange that it has two places since there's the SIFS
> > > too which is needed for ACK/CTS timing, these packets aren't sent from
> > > the host so you can't have those timings in a per-packet descriptor.
> > 
> > You mean things like ACK_TIMEOUT, those are all seperate registers in the Ralink hardware.
> 
> No, I'm not talking about the ack timeout, I'm thinking of the short
> interframe space (SIFS) which you wait after receiving a packet before
> sending the ACK.

ok. That means that my previous point regarding the differences between
the legacy drivers remains valid. ;)

> > ButI think I should be more clearer on this, rt2500pci and rt2500usb are
> > basically the same chipset but only the bus type is different.
> > What is notable is that _only_ rt2500usb has this IFS register, none of the
> > other Ralink chipsets (including rt2500pci) have it.
> 
> That is indeed strange.

:)

> > True, but in G mode you are compatible with B. The legacy driver doesn't
> > switch back to B mode when the AP is in B mode. This means that it will
> > be using the G timing values.
> 
> That sounds wrong.

Not really, this would be the same behavior that you suggested earlier,
when you stated that a driver should perhaps not register 802.11B mode
when also registering 802.11G mode since it is backward compatible.

Ivo