Re: [PATCH net-next v2 3/3] net: stmmac: Set CIC bit only for TX queues with COE

[Jakub Kicinski <kuba@kernel.org>]

On Fri, 22 Aug 2025 18:19:01 +0530 G Thomas, Rohan wrote:
> On 8/21/2025 7:47 PM, Jakub Kicinski wrote:
> >> Currently, in the stmmac driver, even though tmo_request_checksum is not
> >> implemented, checksum offloading is still effectively enabled for AF_XDP
> >> frames, as CIC bit for tx desc are set, which implies checksum
> >> calculation and insertion by hardware for IP packets. So, I'm thinking
> >> it is better to keep it as false only for queues that do not support
> >> COE.  
> > Oh, so the device parses the packet and inserts the checksum whether
> > user asked for it or not? Damn, I guess it may indeed be too late
> > to fix, but that certainly_not_ how AF_XDP is supposed to work.
> > The frame should not be modified without user asking for it..  
> 
> Yes, I also agreed. But since not sure, currently any XDP applications
> are benefiting from hw checksum, I think it's more reasonable to keep
> csum flag as false only for queues that do not support COE, while
> maintaining current behavior for queues that do support it. Please let
> me know if you think otherwise.

Agreed.