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Subject: Re: [PATCH v3 1/7] AMSO1100 Low Level Driver.
From: Steve Wise <swise@opengridcomputing.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: rdreier@cisco.com, mshefty@ichips.intel.com, linux-kernel@vger.kernel.org,
       netdev@vger.kernel.org, openib-general@openib.org
In-Reply-To: <1150836226.2891.231.camel@laptopd505.fenrus.org>
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Date: Fri, 23 Jun 2006 08:44:50 -0500
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> 
> Also on a related note, have you checked the driver for the needed PCI
> posting flushes?
> 
> > +
> > +	/* Disable IRQs by clearing the interrupt mask */
> > +	writel(1, c2dev->regs + C2_IDIS);
> > +	writel(0, c2dev->regs + C2_NIMR0);
> 
> like here...

This code is followed by a call to c2_reset(), which interacts with the
firmware on the adapter to quiesce the hardware.  So I don't think we
need to wait here for the posted writes to flush...

> > +
> > +	elem = tx_ring->to_use;
> > +	elem->skb = skb;
> > +	elem->mapaddr = mapaddr;
> > +	elem->maplen = maplen;
> > +
> > +	/* Tell HW to xmit */
> > +	__raw_writeq(cpu_to_be64(mapaddr), elem->hw_desc + C2_TXP_ADDR);
> > +	__raw_writew(cpu_to_be16(maplen), elem->hw_desc + C2_TXP_LEN);
> > +	__raw_writew(cpu_to_be16(TXP_HTXD_READY), elem->hw_desc + C2_TXP_FLAGS);
> 
> or here
> 

No need here.  This logic submits the packet for transmission.  We don't
assume it is transmitted until we (after a completion interrupt usually)
read back the HTXD entry and see the TXP_HTXD_DONE bit set (see
c2_tx_interrupt()). 


Steve.