Hello everyone, Felix, thanks for the feedback ! On Tue, 8 Nov 2022 13:22:17 +0100 Felix Fietkau <nbd@xxxxxxxx> wrote: [...] > FYI, I'm currently working on hardware DSA untagging on the mediatek > mtk_eth_soc driver. On this hardware, I definitely need to keep the > custom DSA tag driver, as hardware untagging is not always available. > For the receive side, I came up with this patch (still untested) for > using METADATA_HW_PORT_MUX. > It has the advantage of being able to skip the tag protocol rcv ops > call for offload-enabled packets. > > Maybe for the transmit side we could have some kind of netdev feature > or capability that indicates offload support and allows skipping the > tag xmit function as well. > In that case, ipqess could simply use a no-op tag driver. If I'm not mistaken, Florian also proposed a while ago an offload mechanism for taggin/untagging : https://lore.kernel.org/lkml/1438322920.20182.144.camel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/T/ It uses some of the points you're mentionning, such as the netdev feature :) All in all, I'm still a bit confused about the next steps. If I can summarize a bit, we have a lot of approaches, all with advantages and inconvenients, I'll try to summarize the state : - We could simply use the skb extensions as-is, rename the tagger something like "DSA_TAG_IPQDMA" and consider this a way to perform tagging on this specific class of hardware, without trying too hard to make it generic. - We could try to move forward with this mechanism of offloading tagging and untagging from the MAC driver, this would address Florian's first try at this, Felix's use-case and would fit well the IPQESS case - There's the option discussed by Vlad and Jakub to add several frontends, one being a switchev driver, here I'm a bit lost TBH, if we go this way I could definitely use a few pointers from Vlad :) When looking at it from this point of view, option 2 looks pretty promising, but I would like to make sure we're on the same page at that point. On my side, I've tried several approaches for this tagging and so far none are acceptable, for good reasons. I would like to make sure then that I grasp the full picture and I didn't miss other possible ways of addressing this. Thanks everyone for your help ! Maxime
