Problems with GSPI

[Dan Williams]

On Sat, 2008-12-20 at 09:56 +0100, Erwin Authried wrote:
> Am Freitag, den 19.12.2008, 20:12 -0500 schrieb Dan Williams:
> > On Sat, 2008-12-20 at 00:19 +0100, Erwin Authried wrote:
> > > Am Freitag, den 19.12.2008, 16:39 -0500 schrieb Dan Williams:
> > > > On Sun, 2008-12-14 at 12:47 +0100, Erwin Authried wrote:
> > > > > Hi,
> > > > > 
> > > > > I'm using the 88W8686 in GSPI mode, and I have created a if_gspi module
> > > > > to be able to use the libertas driver instead of Marvell's original
> > > > > driver. I tried ad-hoc mode first, and that seems to work fine, I'm
> > > > > getting event interrupts when a link is lost or re-established. In
> > > > > managed mode, I can establish a WEP connection using iwconfig, and I'm
> > > > > getting an interrupt when the link to the AP is lost. I'm not getting
> > > > > any further event interrupts when the link comes back or goes down
> > > > > again, however. With wpa supplicant, everything works fine, but I'd
> > > > > still like to know if it's normal that no events are received in managed
> > > > > mode, except the first event when the link goes down. I'm using firmware
> > > > > version gspi 9.70.3p37, but I have seen the same problem with older
> > > > > firmware and the original Marvell driver as well. I'd like to know if
> > > > > there's the same problem is there with SD and CF.
> > > > 
> > > > Any chance you could try one of the GSPI patches that just got posted?
> > > I can't use those patches directly because my hardware uses a CPLD that
> > > does the serial/parallel conversion. But the comments in the source give
> > > some insight on the correct usage of the registers.
> > > 
> > > > We should try to converge on a single GSPI driver so that we can
> > > > actually try to track down stuff like this.  
> > > I'm thinking about creating a SPI driver for my hardware to make that
> > > possible. 
> > > 
> > > > In response to the actual
> > > > question though, when you say "the link comes back", do you mean that
> > > > the reconnection process initiated by wpa_supplicant is successful and
> > > > eventually reports CONNECTED?  Can you post some wpa_supplicant logs
> > > > with "-dddt" full debugging?  AFAIK MAC events should still be
> > > > generated, though the firmware is sometimes dodgy.  I'd suspect
> > > > something odd in your GSPI code about clearing the interrupt register
> > > > correctly, or handling the event correctly when the event packet comes
> > > > back from the card.  
> > > 
> > > With "the link comes back" I mean that I turn the AP on again. I believe
> > 
> > Ok, so you turn off the AP and turn it back on again?  If that's the
> > case, then no, we don't expect the driver/firmware to reconnect
> > automatically.  That's what the supplicant does through scanning and
> > reconnection.  The driver/firmware won't necessarily continually try to
> > reconnect, because there's no idea when the AP might come back.  When
> > the connection drops, the supplicant will terminate the association in
> > the driver, and enter the scan loop, where it will periodically scan for
> > the highest priority access point and when it's found, try to reconnect.
> > You won't necessarily get unsolicited MAC association events when you
> > turn the AP back on because the association has been torn down already.
> > Roaming/reassoc is done by the supplicant.
> > 
> > So I think what you're seeing is expected.
> > 
> > Dan
> 
> Dan,
> thanks a lot for the explanation. That means that even with WEP only I
> can't work without supplicant, because any short connection loss would
> terminate the connection permanently, right? When I am using ad-hoc
> mode, I get an event everytime the link goes up or down, thus I thought
> that there must be some bug in managed mode.

Correct, once the connection goes down something in userspace is
expected to handle the disconnection, either by attempting a
reassoc/reauth, or by trying a different AP.

Adhoc mode obviously doesn't use a central authority like a base
station, and therefore doesn't have any authentication/association,
being completely peer-to-peer.  Thus link up/link down doesn't really
mean anything here, because no external events (short of unplugging the
card) will actually cause the connection to drop.

Dan