Re: [PATCH net-next] net: stmmac: set total length of the packet to be transmitted in TDES3

[Joao Pinto]

Hi Niklas,

Às 7:33 PM de 4/10/2017, Niklas Cassel escreveu:
> From: Niklas Cassel <niklas.cassel@xxxxxxxx>
> 
> Field FL/TPL in register TDES3 is not correctly set on GMAC4.
> TX appears to be functional on GMAC 4.10a even if this field is not set,
> however, to avoid relying on undefined behavior, set the length in TDES3.
> 
> The field has a different meaning depending on if the TSE bit in TDES3
> is set or not (TSO). However, regardless of the TSE bit, the field is
> not optional. The field is already set correctly when the TSE bit is set.
> 
> Since there is no limit for the number of descriptors that can be
> used for a single packet, the field should be set to the sum of
> the buffers contained in:
> [<desc with First Descriptor bit set> ... <desc n> ...
> <desc with Last Descriptor bit set>], which should be equal to skb->len.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxxx>

Sounds fine to me. Did you check for performance improvement? Thanks.

Joao