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

Felix Fietkau
2022-11-10T18:43:32Z

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