[U-Boot] Net driver questions

[Mike Frysinger <vapier@gentoo.org>]

On Monday 02 November 2009 10:08:00 Krzysztof Halasa wrote:
> Mike Frysinger <vapier@gentoo.org> writes:
> > it's on purpose because it makes the code simpler -- no need to maintain
> > state.  drivers have to be able to handle halt() irregardless of init(). 
> > i dont see this being a problem for anyone.
> 
> Ok. Sure, that's not a problem for me, I just noted the README doesn't
> talk about this.

that's because the README covered whatever i could think of at the time, and i 
basically brain dumped what little i knew of the net framework.  getting more 
people to read & question edge cases is good so those can be filled out.

(i already posted a patch for your first and last point)

> >> - dev->recv() seems to be called recursively, for example while doing
> >>   "dhcp" or "bootp" (ping is ok). dev->recv() in my driver calls
> >>   NetReceive(), which in turn (without returning to the caller, i.e.,
> >>   dev->recv(), first) reinitializes the driver on error (calls
> >>   dev->halt() and dev->init()). This makes a lot of mess in the driver,
> >>   should it stay this way? Perhaps we should queue the received packets
> >>   and process them on return from dev->recv()? Or maybe return all those
> >>   packets together?
> >
> > where exactly do you see that call path ?  i dont see it anywhere ...
> >
> > NetReceive() may call eth_send(), but that only expands into
> > dev->send()
> 
> Let's look... The code does NetSetHandler(TftpHandler).
> I think NetReceive() calls (*packetHandler)() = TftpHandler and this one
> may call NetStartAgain().

but this doesnt call recv(), and NetStartAgain() changes the handler, so i 
still dont see recursion with the recv() function.  but perhaps your 
definition of recursive is different from mine.  recv() does not turn around 
and call recv(), but recv() may turn around and call other driver functions.

the tftp error behavior is to basically discard all pending packets, so in 
practice, it shouldnt be a big deal.  it would probably be cleaner though if 
the packet handler returned an integer indicating errors that NetReceive() 
would pass up so that the driver recv knew to stop processing packets right 
away.  Ben would have to comment here though as this is beyond the extent of 
my networking knowledge.
-mike
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