Hello!
On 11/25/21 1:15 PM, Biju Das wrote:
>>> TOE has hw support for calculating IP header checkum for IPV4 and
>>> TCP/UDP/ICMP checksum for both IPV4 and IPV6.
>>>
>>> This patch adds Rx checksum offload supported by TOE.
>>>
>>> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
>>> ---
>>> drivers/net/ethernet/renesas/ravb.h | 4 +++
>>> drivers/net/ethernet/renesas/ravb_main.c | 31
>>> ++++++++++++++++++++++++
>>> 2 files changed, 35 insertions(+)
>>>
>>> diff --git a/drivers/net/ethernet/renesas/ravb.h
>>> b/drivers/net/ethernet/renesas/ravb.h
>>> index a96552348e2d..d0e5eec0636e 100644
>>> --- a/drivers/net/ethernet/renesas/ravb.h
>>> +++ b/drivers/net/ethernet/renesas/ravb.h
[...]
>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c
>>> b/drivers/net/ethernet/renesas/ravb_main.c
>>> index c2b92c6a6cd2..2533e3401593 100644
>>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
>>> @@ -720,6 +720,33 @@ static void ravb_get_tx_tstamp(struct net_device
[...]
>>> + u8 *hw_csum;
>>> +
>>> + /* The hardware checksum is contained in sizeof(__sum16) * 2 = 4
>> bytes
>>> + * appended to packet data. First 2 bytes is ip header csum and last
>>> + * 2 bytes is protocol csum.
>>> + */
>>> + if (unlikely(skb->len < sizeof(__sum16) * 2))
>>> + return;
>>> + hw_csum = skb_tail_pointer(skb) - sizeof(__sum16);
>>> + csum_proto = csum_unfold((__force
>>> +__sum16)get_unaligned_le16(hw_csum));
>>> +
>>> + hw_csum = skb_tail_pointer(skb) - 2 * sizeof(__sum16);
>>> + csum_ip_hdr = csum_unfold((__force
>>> +__sum16)get_unaligned_le16(hw_csum));
>>> +
>>> + skb->ip_summed = CHECKSUM_NONE;
>>> + if (csum_proto == TOE_RX_CSUM_OK) {
>>> + if (skb->protocol == htons(ETH_P_IP) && csum_ip_hdr ==
>> TOE_RX_CSUM_OK)
>>> + skb->ip_summed = CHECKSUM_UNNECESSARY;
>>> + else if (skb->protocol == htons(ETH_P_IPV6) &&
>>> + csum_ip_hdr == TOE_RX_CSUM_UNSUPPORTED)
>>> + skb->ip_summed = CHECKSUM_UNNECESSARY;
>>
>> Checksum is unsupported and you declare it unnecessary?
>
>
> Do you mean takeout the check for unsupported headercsum for IPV6 and the code like one below?
No, I meant that the code looks strange.
> If(!csum_proto) {
> if ((skb->protocol == htons(ETH_P_IP) && !csum_ip_hdr) || skb->protocol == htons(ETH_P_IPV6))
I think this statement doesn't make sense, unless the TOE itself doesn't check the protocol ID in
the Ethernet frame (which it should). It also seems (after reading <linux/skbuff.h>) that enabling
IPv4 header checksum calculation is pointless -- you don't have the means to report it anyway...
You may want to set skb-csum_level though (not sure if that's not already 0).
> skb->ip_summed = CHECKSUM_UNNECESSARY;
> }
>
> Snippet from H/W manual for reception handling
>
> (1) Reception Handling
> The result of Checksum Calculation is attached to last 4 byte of Ethernet Frames like Figure 30.25. And then the
> handled frames are transferred to memory by DMAC. If the frame does not have checksum error at the part of IPv4
> Header or TCP/UDP/ICMP, the value of “0000h” is attached to each part as the result of Checksum Calculation. The
> case of Unsupported Frame, the value of “FFFFh” is attached. For example, if the part of IP Header is unsupported,
> “FFFFh” is set to both field of IPv4 Header and TCP/UDP/ICMP. The case of IPv6, IPv4 Header field is always set to
> “FFFFh”.
>
>
>>
>>> + }
>>
>> Now where's a call to skb_trim()?
>
> Currently I haven't seen any issue without using skb_trim.
>
> OK, as you suggested, will check and add skb_trim to takeout the last 4bytes.
We do it for EtherAVB, why not do it for GbEther?
> Regards,
> Biju
MBR, Sergey
