Subject: Re: [PATCH net-next 5/8] net: ethernet: mtk_eth_soc: add MTK_NETSYS_V3 capability bit

From: "Russell King (Oracle)" <[email-masked]>
Date: Mon, 12 Jun 2023 12:19:52 +0100

On Sun, Jun 11, 2023 at 01:38:23AM +0100, Daniel Golle wrote:
> @@ -1333,8 +1354,13 @@ static int mtk_tx_map(struct sk_buff *skb, struct net_device *dev,
>  	mtk_tx_set_dma_desc(dev, itxd, &txd_info);
>  
>  	itx_buf->flags |= MTK_TX_FLAGS_SINGLE0;
> -	itx_buf->flags |= (!mac->id) ? MTK_TX_FLAGS_FPORT0 :
> -			  MTK_TX_FLAGS_FPORT1;
> +	if (mac->id == MTK_GMAC1_ID)
> +		itx_buf->flags |= MTK_TX_FLAGS_FPORT0;
> +	else if (mac->id == MTK_GMAC2_ID)
> +		itx_buf->flags |= MTK_TX_FLAGS_FPORT1;
> +	else
> +		itx_buf->flags |= MTK_TX_FLAGS_FPORT2;

There appears to be two places that this code structure appears, and
this is in the path for packet transmission. I wonder if it would be
more efficient to instead do:

	itx_buf->flags |= MTK_TX_FLAGS_SINGLE0 | mac->tx_flags;

with mac->tx_flags appropriately initialised?

> @@ -2170,7 +2214,9 @@ static int mtk_poll_tx_qdma(struct mtk_eth *eth, int budget,
>  		tx_buf = mtk_desc_to_tx_buf(ring, desc,
>  					    eth->soc->txrx.txd_size);
>  		if (tx_buf->flags & MTK_TX_FLAGS_FPORT1)
> -			mac = 1;
> +			mac = MTK_GMAC2_ID;
> +		else if (tx_buf->flags & MTK_TX_FLAGS_FPORT2)
> +			mac = MTK_GMAC3_ID;

This has me wondering whether the flags are used for hardware or just
for the driver's purposes. If it's the latter, can we instead store the
MAC index in tx_buf, rather than having to decode a bitfield?

I suspect these are just for the driver given that the addition of
MTK_TX_FLAGS_FPORT2 changes all subsequent bit numbers in this struct
member.

>  
>  		if (!tx_buf->data)
>  			break;
> @@ -3783,7 +3829,26 @@ static int mtk_hw_init(struct mtk_eth *eth, bool reset)
>  	mtk_w32(eth, eth->soc->txrx.rx_irq_done_mask, reg_map->qdma.int_grp + 4);
>  	mtk_w32(eth, 0x21021000, MTK_FE_INT_GRP);
>  
> -	if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2)) {
> +	if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V3)) {
> +		/* PSE should not drop port1, port8 and port9 packets */
> +		mtk_w32(eth, 0x00000302, PSE_DROP_CFG);
> +
> +		/* GDM and CDM Threshold */
> +		mtk_w32(eth, 0x00000707, MTK_CDMW0_THRES);
> +		mtk_w32(eth, 0x00000077, MTK_CDMW1_THRES);
> +
> +		/* Disable GDM1 RX CRC stripping */
> +		val = mtk_r32(eth, MTK_GDMA_FWD_CFG(0));
> +		val &= ~MTK_GDMA_STRP_CRC;
> +		mtk_w32(eth, val, MTK_GDMA_FWD_CFG(0));

mtk_m32() ?

Thanks!

-- 
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