Re: [PATCH net v2 1/6] net: stmmac: Remove VLAN perfect matching dead code

[Maxime Chevallier]

Hi Ovidiu,

On 8/21/26 19:09, Ovidiu Panait wrote:
> stmmac_vlan_update() falls back to "perfect matching" when the VLAN hash
> filter is unavailable (!priv->dma_cap.vlhash). This fallback has been
> unreachable in normal operation since its introduction in
> commit c7ab0b8088d7 ("net: stmmac: Fallback to VLAN Perfect filtering if
> HASH is not available") because the NETIF_F_HW_VLAN_{CTAG,STAG}_FILTER
> features are advertised only when priv->dma_cap.vlhash is true.
> 
> The fallback is also duplicating the code in vlan_add_hw_rx_fltr(), which
> is always available since stmmac_get_num_vlan() returns at least 1.
> 
> Therefore, remove it.
> 
> Fixes: c7ab0b8088d7 ("net: stmmac: Fallback to VLAN Perfect filtering if HASH is not available")
> Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@xxxxxxxxxxx>

Reviewed-by: Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>

Maxime

> ---
> v2 changes: None.
> 
>  drivers/net/ethernet/stmicro/stmmac/hwif.h    |  2 +-
>  .../net/ethernet/stmicro/stmmac/stmmac_main.c | 13 +-----
>  .../net/ethernet/stmicro/stmmac/stmmac_vlan.c | 41 +------------------
>  3 files changed, 4 insertions(+), 52 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.h b/drivers/net/ethernet/stmicro/stmmac/hwif.h
> index 04dafec021b4..6f26dbf95ce1 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/hwif.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/hwif.h
> @@ -633,7 +633,7 @@ struct stmmac_est_ops {
>  struct stmmac_vlan_ops {
>  	/* VLAN */
>  	void (*update_vlan_hash)(struct mac_device_info *hw, u32 hash,
> -				 u16 perfect_match, bool is_double);
> +				 bool is_double);
>  	void (*enable_vlan)(struct mac_device_info *hw, u32 type);
>  	void (*rx_hw_vlan)(struct mac_device_info *hw, struct dma_desc *rx_desc,
>  			   struct sk_buff *skb);
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index b2b7d0242dd3..16fe56a1f617 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -6809,29 +6809,18 @@ static u32 stmmac_vid_crc32_le(__le16 vid_le)
>  static int stmmac_vlan_update(struct stmmac_priv *priv, bool is_double)
>  {
>  	u32 crc, hash = 0;
> -	u16 pmatch = 0;
> -	int count = 0;
>  	u16 vid = 0;
>  
>  	for_each_set_bit(vid, priv->active_vlans, VLAN_N_VID) {
>  		__le16 vid_le = cpu_to_le16(vid);
>  		crc = bitrev32(~stmmac_vid_crc32_le(vid_le)) >> 28;
>  		hash |= (1 << crc);
> -		count++;
> -	}
> -
> -	if (!priv->dma_cap.vlhash) {
> -		if (count > 2) /* VID = 0 always passes filter */
> -			return -EOPNOTSUPP;
> -
> -		pmatch = vid;
> -		hash = 0;
>  	}
>  
>  	if (!netif_running(priv->dev))
>  		return 0;
>  
> -	return stmmac_update_vlan_hash(priv, priv->hw, hash, pmatch, is_double);
> +	return stmmac_update_vlan_hash(priv, priv->hw, hash, is_double);
>  }
>  
>  /* FIXME: This may need RXC to be running, but it may be called with BH
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c
> index e24efe3bfedb..983a90cb9767 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c
> @@ -162,7 +162,7 @@ static void vlan_restore_hw_rx_fltr(struct net_device *dev,
>  }
>  
>  static void vlan_update_hash(struct mac_device_info *hw, u32 hash,
> -			     u16 perfect_match, bool is_double)
> +			     bool is_double)
>  {
>  	void __iomem *ioaddr = hw->pcsr;
>  	u32 value;
> @@ -184,20 +184,6 @@ static void vlan_update_hash(struct mac_device_info *hw, u32 hash,
>  		}
>  
>  		writel(value, ioaddr + VLAN_TAG);
> -	} else if (perfect_match) {
> -		u32 value = VLAN_ETV;
> -
> -		if (is_double) {
> -			value |= VLAN_EDVLP;
> -			value |= VLAN_ESVL;
> -			value |= VLAN_DOVLTC;
> -		} else {
> -			value &= ~VLAN_EDVLP;
> -			value &= ~VLAN_ESVL;
> -			value &= ~VLAN_DOVLTC;
> -		}
> -
> -		writel(value | perfect_match, ioaddr + VLAN_TAG);
>  	} else {
>  		value &= ~(VLAN_VTHM | VLAN_ETV);
>  		value &= ~(VLAN_EDVLP | VLAN_ESVL);
> @@ -251,7 +237,7 @@ static void vlan_set_hw_mode(struct mac_device_info *hw)
>  }
>  
>  static void dwxgmac2_update_vlan_hash(struct mac_device_info *hw, u32 hash,
> -				      u16 perfect_match, bool is_double)
> +				      bool is_double)
>  {
>  	void __iomem *ioaddr = hw->pcsr;
>  
> @@ -279,29 +265,6 @@ static void dwxgmac2_update_vlan_hash(struct mac_device_info *hw, u32 hash,
>  
>  		value &= ~VLAN_VID;
>  		writel(value, ioaddr + VLAN_TAG);
> -	} else if (perfect_match) {
> -		u32 value = readl(ioaddr + XGMAC_PACKET_FILTER);
> -
> -		value |= XGMAC_FILTER_VTFE;
> -
> -		writel(value, ioaddr + XGMAC_PACKET_FILTER);
> -
> -		value = readl(ioaddr + VLAN_TAG);
> -
> -		value &= ~VLAN_VTHM;
> -		value |= VLAN_ETV;
> -		if (is_double) {
> -			value |= VLAN_EDVLP;
> -			value |= VLAN_ESVL;
> -			value |= VLAN_DOVLTC;
> -		} else {
> -			value &= ~VLAN_EDVLP;
> -			value &= ~VLAN_ESVL;
> -			value &= ~VLAN_DOVLTC;
> -		}
> -
> -		value &= ~VLAN_VID;
> -		writel(value | perfect_match, ioaddr + VLAN_TAG);
>  	} else {
>  		u32 value = readl(ioaddr + XGMAC_PACKET_FILTER);
>