On 10/7/21 8:49 AM, Biju Das wrote:
[...]
>>>>> Fillup ravb_rx_gbeth() function to support RZ/G2L.
>>>>>
>>>>> This patch also renames ravb_rcar_rx to ravb_rx_rcar to be
>>>>> consistent with the naming convention used in sh_eth driver.
>>>>>
>>>>> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
>>>>> Reviewed-by: Lad Prabhakar
>>>>> <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>[...]
>>>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c
>>>>> b/drivers/net/ethernet/renesas/ravb_main.c
>>>>> index 37164a983156..42573eac82b9 100644
>>>>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>>>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
>>>>> @@ -720,6 +720,23 @@ static void ravb_get_tx_tstamp(struct
>>>>> net_device
>>>> *ndev)
>>>>> }
>>>>> }
>>>>>
>>>>> +static void ravb_rx_csum_gbeth(struct sk_buff *skb) {
>>>>> + u8 *hw_csum;
>>>>> +
>>>>> + /* The hardware checksum is contained in sizeof(__sum16) (2) bytes
>>>>> + * appended to packet data
>>>>> + */
>>>>> + if (unlikely(skb->len < sizeof(__sum16)))
>>>>> + return;
>>>>> + hw_csum = skb_tail_pointer(skb) - sizeof(__sum16);
>>>>
>>>> Not 32-bit? The manual says the IP checksum is stored in the first
>>>> 2 bytes.
>>>
>>> It is 16 bit. It is on last 2 bytes.
The IP checksum is at the 1st 2 bytes of the overall 4-byte checksum (coming after
the packet payload), no?
>> So you're saying the manual is wrong?
>
> I am not sure which manual you are referring here.
>
> I am referring to Rev.1.00 Sep, 2021 of RZ/G2L hardware manual and
Same here.
[...]
> Please check the section 30.5.6.1 checksum calculation handling> And figure 30.25 the field of checksum attaching field
I have.
> Also see Table 30.17 for checksum values for non-error conditions.
> TCP/UDP/ICPM checksum is at last 2bytes.
What are you arguing with then? :-)
My point was that your code fetched the TCP/UDP/ICMP checksum ISO the IP checksum
because it subtracts sizeof(__sum16), while should probably subtract sizeof(__wsum).
>>>>> +
>>>>> + if (*hw_csum == 0)
>>>>
>>>> You only check the 1st byte, not the full checksum!
>>>
>>> As I said earlier, "0" value on last 16 bit, means no checksum error.
>>
>> How's that? 'hw_csum' is declared as 'u8 *'!
>
> It is my mistake, which will be taken care in the next patch by using u16 *.
Note that this 'u16' halfword can be unaligned, that's why the current code uses get_unaligned_le16().
>>>>> + skb->ip_summed = CHECKSUM_UNNECESSARY;
>>>>> + else
>>>>> + skb->ip_summed = CHECKSUM_NONE;
>>>>
>>>> So the TCP/UDP/ICMP checksums are not dealt with? Why enable them
>> then?
>>>
>>> If last 2bytes is zero, means there is no checksum error w.r.to
>> TCP/UDP/ICMP checksums.
>>
>> Why checksum them independently then?
>
> It is a hardware feature.
Switchable, isn't it?
> Regards,
> Biju
[...]
MBR, Sergey
