From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Lunn <andrew@lunn.ch>
Subject: Re: [ISSUE: sky2 - rx error] Link stops working under heavy traffic
 load connected to a mv88e6176
Date: Tue, 16 May 2017 15:21:16 +0200
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Cc: Stephen Hemminger <stephen@networkplumber.org>,
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To: Rafa Corvillo <rafael.corvillo@aoifes.com>
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On Tue, May 16, 2017 at 03:09:17PM +0200, Rafa Corvillo wrote:
> >>Adding 8 bytes (sky2->netdev->mtu + ETH_HLEN + VLAN_HLEN + 8
> >>(EDSA_HLEN)) does not fix the error, because the interface keep
> >>having a maximum length of 1518 bytes (sky2->netdev->mtu + ETH_HLEN
> >>+ VLAN_HLEN).
> >
> >Did you check the value being written to here:
> >
> >         /*
> >          * The receiver hangs if it receives frames larger than the
> >          * packet buffer. As a workaround, truncate oversize frames, but
> >          * the register is limited to 9 bits, so if you do frames > 2052
> >          * you better get the MTU right!
> >          */
> >         thresh = sky2_get_rx_threshold(sky2);
> >         if (thresh > 0x1ff)
> >                 sky2_write32(hw, SK_REG(sky2->port, RX_GMF_CTRL_T), RX_TRUNC_OFF);
> >         else {
> >                 sky2_write16(hw, SK_REG(sky2->port, RX_GMF_TR_THR), thresh);
> >                 sky2_write32(hw, SK_REG(sky2->port, RX_GMF_CTRL_T), RX_TRUNC_ON);
> >         }
> >
> >
> >What is thresh?
> 
> The value of thresh is 380.

So that is 1528.

You could hack it and try 0x1ff.

Also, check that in sky2_rx_add(), le->length is set to 4K.

      Andrew