Re: [Qemu-devel] [PATCH 1/2] e1000: no need auto-negotiation if link was down

[Amos Kong]

On Sat, Jan 05, 2013 at 04:45:14PM +0800, Jason Wang wrote:
> On 01/03/2013 08:20 PM, Stefan Hajnoczi wrote:
> > On Fri, Dec 28, 2012 at 05:29:10PM +0800, Amos Kong wrote:
> >> Commit b9d03e352cb6b31a66545763f6a1e20c9abf0c2c added link
> >> auto-negotiation emulation, it would always set link up by
> >> callback function. Problem exists if original link status
> >> was down, link status should not be changed in auto-negotiation.
> >>
> >> Signed-off-by: Jason Wang <address@hidden>
> >> Signed-off-by: Amos Kong <address@hidden>
> >> ---
> >>  hw/e1000.c |    5 +++++
> >>  1 file changed, 5 insertions(+)
> >>
> >> diff --git a/hw/e1000.c b/hw/e1000.c
> >> index 92fb00a..eebcd1d 100644
> >> --- a/hw/e1000.c
> >> +++ b/hw/e1000.c
> >> @@ -164,6 +164,11 @@ static void
> >>  set_phy_ctrl(E1000State *s, int index, uint16_t val)
> >>  {
> >>      if ((val & MII_CR_AUTO_NEG_EN) && (val & MII_CR_RESTART_AUTO_NEG)) {
> >> +        /* no need auto-negotiation if link was down */
> >> +        if (s->nic->nc.link_down) {
> >> +            s->phy_reg[PHY_STATUS] |= MII_SR_AUTONEG_COMPLETE;
> >> +            return;
> >> +        }
> >>          s->nic->nc.link_down = true;
> >>          e1000_link_down(s);
> >>          s->phy_reg[PHY_STATUS] &= ~MII_SR_AUTONEG_COMPLETE;
> > Do we need set_ics(s, 0, E1000_ICR_LSC) when autonegotiation completes?
> > The code doesn't but I wonder if we should.
> 
> Not in this case I think. The hack of the auto-negotiation was used to
> prevent the irq to be injected before the handler is registered in
> windows guest. So an irq would be raised here if we do this which breaks
> the hack.

In e1000_open(), after enable irq of adapter, driver will fire a link status
change interrupt to start a watchdog, which will update the link status in
system.

After auto-nego complete, the irq of adapter is still not enabled, the
early interrupt will not work.

So current code is ok.

Thanks, Amos

> > Stefan