netdev - Re: Re: Strange connection slowdown on pcnet32

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Message-ID: <20070219235916.GL7585@csclub.uwaterloo.ca>
Date:	Mon, 19 Feb 2007 18:59:16 -0500
From:	lsorense@...lub.uwaterloo.ca (Lennart Sorensen)
To:	pcnet32@...izon.net
Cc:	netdev@...r.kernel.org
Subject: Re: Re: Strange connection slowdown on pcnet32

On Mon, Feb 19, 2007 at 06:45:48PM -0500, Lennart Sorensen wrote:
> It seems the problem actually occours when the receive descriptor ring
> is full.  This seems to generate one (or sometimes more) descriptors in
> the ring which claim to be owned by the MAC, but at the head of the
> receive ring as far as the driver is concerned.  I see some note in the
> driver about an SP3G chipset sometimes causing this.  How would one
> identify this and clear such descriptors out of the way?  Getting stuck
> until the next time the MAC gets around to the descriptor and overwrites
> it is not good, since it causes delays, and out of order packets.

I am also noticing the receive error count going up, and the source is
this code:

if (status & 0x01)      /* Only count a general error at the */
       lp->stats.rx_errors++;  /* end of a packet. */

It appears this means I am receiving a frame marked with "End Of Packet"
but without "Start of Packet".  I have no idea how that happens, but it
shouldn't be able to make the driver and MAC stop processing the receive
ring.

--
Len Sorensen
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