From mboxrd@z Thu Jan  1 00:00:00 1970
From: Greg Ungerer <gerg@kernel.org>
Subject: Re: [PATCH 0/3]: net: dsa: mt7530: support MT7530 in the MT7621 SoC
Date: Fri, 30 Nov 2018 23:45:13 +1000
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 <20181130133751.GC11747@lunn.ch>
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To: Andrew Lunn <andrew@lunn.ch>
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Hi Andrew,

On 30/11/18 11:37 pm, Andrew Lunn wrote:
>> 1. TX packets are not getting an IP header checksum via the normal
>>     off-loaded checksumming when in DSA mode. I have to switch off
>>     NETIF_F_IP_CSUM, so the software stack generates the checksum.
>>     That checksum offloading works ok when not using the 7530 DSA driver.
> 
> With some vendors MAC hardware, there is a field in the descriptor to
> indicate how big a VLAN tag the frame has. The hardware can then use
> this information to skip over the VLAN tags to find the IP header, and
> then perform checksuming. You might be able to re-use that, consider
> the DSA header as part of the VLAN header.
> 
> Other vendors, there is no way i've found to get hadware offload of
> checksumming working.

Thanks for the tips, I will try out the master mtu change too.

Regards
Greg