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Date: Mon, 1 Feb 2010 14:51:37 -0800
From: Stephen Hemminger <shemminger@vyatta.com>
To: Jarek Poplawski <jarkao2@gmail.com>
Cc: Michael Breuer <mbreuer@majjas.com>, David Miller <davem@davemloft.net>,
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       Michael Chan <mchan@broadcom.com>, Don Fry <pcnet32@verizon.net>,
       Francois Romieu <romieu@fr.zoreil.com>,
       Matt Carlson <mcarlson@broadcom.com>
Subject: Re: [PATCH v3] sky2:  receive dma mapping error handling
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On Mon, 1 Feb 2010 23:46:39 +0100
Jarek Poplawski <jarkao2@gmail.com> wrote:

> On Mon, Feb 01, 2010 at 02:29:42PM -0800, Stephen Hemminger wrote:
> > On Mon, 1 Feb 2010 22:27:41 +0100
> > Jarek Poplawski <jarkao2@gmail.com> wrote:
> > 
> > > @@ -1038,13 +1035,14 @@ static void tx_init(struct sky2_port *sky2)
> > >  {
> > >  	struct sky2_tx_le *le;
> > >  
> > > -	sky2->tx_prod = sky2->tx_cons = 0;
> > > +	sky2->tx_prod = 0;
> > >  	sky2->tx_tcpsum = 0;
> > >  	sky2->tx_last_mss = 0;
> > >  
> > >  	le = get_tx_le(sky2, &sky2->tx_prod);
> > >  	le->addr = 0;
> > >  	le->opcode = OP_ADDR64 | HW_OWNER;
> > > +	sky2->tx_cons = sky2->tx_prod;
> > >  	sky2->tx_last_upper = 0;
> > >  }
> > 
> > Your change causes the initial element to be skipped. I want
> > it to goto the hardware. It makes sure the upper bits of the
> > first request are set (0).
> 
> I thought "Send high bits if needed" part in sky2_xmit_frame() was
> enough. If it's otherwise than my patch was wrong.
> 

The definition is "high bits are different than the last value".
The code init sets the last value to zero, and initializes the hardware
engine as well.