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Message-ID: <516EB4F8.2090004@mentor.com>
Date: Wed, 17 Apr 2013 15:43:04 +0100
From: Jim Baxter <jim_baxter@...tor.com>
To: Ben Hutchings <bhutchings@...arflare.com>
CC: "David S. Miller" <davem@...emloft.net>,
Frank Li <Frank.Li@...escale.com>,
Fugang Duan <B38611@...escale.com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v2 1/1] net: fec: Enable imx6 enet checksum acceleration.
On 16/04/13 23:41, Ben Hutchings wrote:
> On Tue, 2013-04-16 at 23:15 +0100, Jim Baxter wrote:
>> On 16/04/13 16:39, Ben Hutchings wrote:
> [...]
>>>> @@ -818,6 +890,19 @@ fec_enet_rx(struct net_device *ndev, int budget)
>>>> spin_unlock_irqrestore(&fep->tmreg_lock, flags);
>>>> }
>>>>
>>>> + if (fep->bufdesc_ex &&
>>>> + (fep->csum_flags & FLAG_RX_CSUM_ENABLED)) {
>>>> + struct bufdesc_ex *ebdp =
>>>> + (struct bufdesc_ex *)bdp;
>>>> + if (!(ebdp->cbd_esc & FLAG_RX_CSUM_ENABLED)) {
>>>> + /* don't check it */
>>>> + skb->ip_summed = CHECKSUM_UNNECESSARY;
>>>
>>> This looks very strange. Presumably the RX_ICE and RX_PCR flags
>>> indicate checksum errors, and therefore !(ebdp->cbd_esc &
>>> FLAG_RX_CSUM_ENABLED) means the checksum(s) are good? This would be
>>> clearer if you defined FLAG_RX_CSUM_ERROR as well (with the same numeric
>>> value).
>>>
>> Agreed, that would be clearer.
>>>> + } else {
>>>> + ndev->stats.rx_errors++;
>>>
>>> Layer 3 and 4 errors should not be counted in the net device stats.
>>>
>> Ok, are they just for Levls 1 and 2?
> [...]
>
> Right, that's my understanding. Our job as driver writers is to
> validate at layer 1 and 2 (FCS error, length error, MAC filtering).
> Checksum validation at layers 3 and 4 is an optimisation and the kernel
> stack takes care of counting checksum errors.
>
> Ben.
>
Thanks for that information Ben, that is good to know.
Has anyone used ping6 or iperf -V, whilst debugging I have found that
the packets being sent are of protocol 0x0800 when using those commands.
Jim
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