Re: [PATCH net-next v2 09/12] net: ethernet: mtk_eth_soc: fix VLAN rx hardware acceleration

[Felix Fietkau]

On 10.11.22 16:22, Vladimir Oltean wrote:
> On Wed, Nov 09, 2022 at 05:34:23PM +0100, Felix Fietkau wrote:
> > - enable VLAN untagging for PDMA rx
> > - make it possible to disable the feature via ethtool
> > - pass VLAN tag to the DSA driver
> > - untag special tag on PDMA only if no non-DSA devices are in use
> > - disable special tag untagging on 7986 for now, since it's not working yet
>
> Each of these bullet points should be its own patch, really.
> "Fix VLAN rx hardware acceleration" isn't doing much to describe them
> and their motivation.
I think some minor things could be split off, but doing one patch per 
bullet point definitely does not make sense.

> >  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 99 ++++++++++++++++-----
> >  drivers/net/ethernet/mediatek/mtk_eth_soc.h |  8 ++
> >  2 files changed, 84 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > index 92bdd69eed2e..ffaa9fe32b14 100644
> > --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > @@ -23,6 +23,7 @@
> >  #include <linux/jhash.h>
> >  #include <linux/bitfield.h>
> >  #include <net/dsa.h>
> > +#include <net/dst_metadata.h>
> >  
> >  #include "mtk_eth_soc.h"
> >  #include "mtk_wed.h"
> > @@ -2008,23 +2009,27 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
> >  		if (reason == MTK_PPE_CPU_REASON_HIT_UNBIND_RATE_REACHED)
> >  			mtk_ppe_check_skb(eth->ppe[0], skb, hash);
> >  
> > -		if (netdev->features & NETIF_F_HW_VLAN_CTAG_RX) {
> > -			if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2)) {
> > -				if (trxd.rxd3 & RX_DMA_VTAG_V2)
> > -					__vlan_hwaccel_put_tag(skb,
> > -						htons(RX_DMA_VPID(trxd.rxd4)),
> > -						RX_DMA_VID(trxd.rxd4));
> > -			} else if (trxd.rxd2 & RX_DMA_VTAG) {
> > -				__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
> > -						       RX_DMA_VID(trxd.rxd3));
> > -			}
> > +		if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2)) {
> > +			if (trxd.rxd3 & RX_DMA_VTAG_V2)
> > +				__vlan_hwaccel_put_tag(skb,
> > +					htons(RX_DMA_VPID(trxd.rxd4)),
> > +					RX_DMA_VID(trxd.rxd4));
> > +		} else if (trxd.rxd2 & RX_DMA_VTAG) {
> > +			__vlan_hwaccel_put_tag(skb, htons(RX_DMA_VPID(trxd.rxd3)),
> > +					       RX_DMA_VID(trxd.rxd3));
> > +		}
> > +
> > +		/* When using VLAN untagging in combination with DSA, the
> > +		 * hardware treats the MTK special tag as a VLAN and untags it.
> > +		 */
> > +		if (skb_vlan_tag_present(skb) && netdev_uses_dsa(netdev)) {
> > +			unsigned int port = ntohs(skb->vlan_proto) & GENMASK(2, 0);
> > +
> > +			if (port < ARRAY_SIZE(eth->dsa_meta) &&
> > +			    eth->dsa_meta[port])
> > +				skb_dst_set_noref(skb, &eth->dsa_meta[port]->dst);
>
> Why _noref?
In order to avoid the cost of unnecessary refcounting. The metadata dst 
is only held until dsa_switch_rcv processes it, after which it is 
removed. The driver only frees it after all its netdevs have been 
unregistered.

- Felix