Subject: Re: [PATCH net-next v2 2/2] net: renesas: rswitch: Use hardware pause features

From: Maciej Fijalkowski <[email-masked]>
Date: Tue, 6 Jun 2023 19:54:31 +0200

On Tue, Jun 06, 2023 at 05:55:58PM +0900, Yoshihiro Shimoda wrote:
> Use "per priority pause" feature of GWCA and "global pause" feature of
> COMA instead of "global rate limiter" of GWCA. Otherwise TX performance
> will be low when we use multiple ports at the same time.

does it mean that global pause feature is completely useless?

> 
> Note that these features are not related to the ethernet PAUSE frame.
> 
> Signed-off-by: Yoshihiro Shimoda <[email-masked]>
> ---
>  drivers/net/ethernet/renesas/rswitch.c | 36 ++++++++++----------------
>  drivers/net/ethernet/renesas/rswitch.h |  6 +++++
>  2 files changed, 20 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> index 7bb0a6d594a0..84f62c77eb8f 100644
> --- a/drivers/net/ethernet/renesas/rswitch.c
> +++ b/drivers/net/ethernet/renesas/rswitch.c
> @@ -90,6 +90,11 @@ static int rswitch_bpool_config(struct rswitch_private *priv)
>  	return rswitch_reg_wait(priv->addr, CABPIRM, CABPIRM_BPR, CABPIRM_BPR);
>  }
>  
> +static void rswitch_coma_init(struct rswitch_private *priv)
> +{
> +	iowrite32(CABPPFLC_INIT_VALUE, priv->addr + CABPPFLC0);
> +}
> +
>  /* R-Switch-2 block (TOP) */
>  static void rswitch_top_init(struct rswitch_private *priv)
>  {
> @@ -156,24 +161,6 @@ static int rswitch_gwca_axi_ram_reset(struct rswitch_private *priv)
>  	return rswitch_reg_wait(priv->addr, GWARIRM, GWARIRM_ARR, GWARIRM_ARR);
>  }
>  
> -static void rswitch_gwca_set_rate_limit(struct rswitch_private *priv, int rate)
> -{
> -	u32 gwgrlulc, gwgrlc;
> -
> -	switch (rate) {
> -	case 1000:
> -		gwgrlulc = 0x0000005f;
> -		gwgrlc = 0x00010260;
> -		break;
> -	default:
> -		dev_err(&priv->pdev->dev, "%s: This rate is not supported (%d)\n", __func__, rate);
> -		return;
> -	}
> -
> -	iowrite32(gwgrlulc, priv->addr + GWGRLULC);
> -	iowrite32(gwgrlc, priv->addr + GWGRLC);
> -}
> -
>  static bool rswitch_is_any_data_irq(struct rswitch_private *priv, u32 *dis, bool tx)
>  {
>  	u32 *mask = tx ? priv->gwca.tx_irq_bits : priv->gwca.rx_irq_bits;
> @@ -402,7 +389,7 @@ static int rswitch_gwca_queue_format(struct net_device *ndev,
>  	linkfix->die_dt = DT_LINKFIX;
>  	rswitch_desc_set_dptr(linkfix, gq->ring_dma);
>  
> -	iowrite32(GWDCC_BALR | (gq->dir_tx ? GWDCC_DQT : 0) | GWDCC_EDE,
> +	iowrite32(GWDCC_BALR | (gq->dir_tx ? GWDCC_DCP(GWCA_IPV_NUM) | GWDCC_DQT : 0) | GWDCC_EDE,
>  		  priv->addr + GWDCC_OFFS(gq->index));
>  
>  	return 0;
> @@ -500,7 +487,8 @@ static int rswitch_gwca_queue_ext_ts_format(struct net_device *ndev,
>  	linkfix->die_dt = DT_LINKFIX;
>  	rswitch_desc_set_dptr(linkfix, gq->ring_dma);
>  
> -	iowrite32(GWDCC_BALR | (gq->dir_tx ? GWDCC_DQT : 0) | GWDCC_ETS | GWDCC_EDE,
> +	iowrite32(GWDCC_BALR | (gq->dir_tx ? GWDCC_DCP(GWCA_IPV_NUM) | GWDCC_DQT : 0) |
> +		  GWDCC_ETS | GWDCC_EDE,
>  		  priv->addr + GWDCC_OFFS(gq->index));
>  
>  	return 0;
> @@ -649,7 +637,8 @@ static int rswitch_gwca_hw_init(struct rswitch_private *priv)
>  	iowrite32(lower_32_bits(priv->gwca.ts_queue.ring_dma), priv->addr + GWTDCAC10);
>  	iowrite32(upper_32_bits(priv->gwca.ts_queue.ring_dma), priv->addr + GWTDCAC00);
>  	iowrite32(GWCA_TS_IRQ_BIT, priv->addr + GWTSDCC0);
> -	rswitch_gwca_set_rate_limit(priv, priv->gwca.speed);
> +
> +	iowrite32(GWTPC_PPPL(GWCA_IPV_NUM), priv->addr + GWTPC0);
>  
>  	for (i = 0; i < RSWITCH_NUM_PORTS; i++) {
>  		err = rswitch_rxdmac_init(priv, i);
> @@ -1502,7 +1491,8 @@ static netdev_tx_t rswitch_start_xmit(struct sk_buff *skb, struct net_device *nd
>  	rswitch_desc_set_dptr(&desc->desc, dma_addr);
>  	desc->desc.info_ds = cpu_to_le16(skb->len);
>  
> -	desc->info1 = cpu_to_le64(INFO1_DV(BIT(rdev->etha->index)) | INFO1_FMT);
> +	desc->info1 = cpu_to_le64(INFO1_DV(BIT(rdev->etha->index)) |
> +				  INFO1_IPV(GWCA_IPV_NUM) | INFO1_FMT);
>  	if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) {
>  		struct rswitch_gwca_ts_info *ts_info;
>  
> @@ -1772,6 +1762,8 @@ static int rswitch_init(struct rswitch_private *priv)
>  	if (err < 0)
>  		return err;
>  
> +	rswitch_coma_init(priv);
> +
>  	err = rswitch_gwca_linkfix_alloc(priv);
>  	if (err < 0)
>  		return -ENOMEM;
> diff --git a/drivers/net/ethernet/renesas/rswitch.h b/drivers/net/ethernet/renesas/rswitch.h
> index b3e0411b408e..08dadd28001e 100644
> --- a/drivers/net/ethernet/renesas/rswitch.h
> +++ b/drivers/net/ethernet/renesas/rswitch.h
> @@ -48,6 +48,7 @@
>  #define GWCA_NUM_IRQS		8
>  #define GWCA_INDEX		0
>  #define AGENT_INDEX_GWCA	3
> +#define GWCA_IPV_NUM		0
>  #define GWRO			RSWITCH_GWCA0_OFFSET
>  
>  #define GWCA_TS_IRQ_RESOURCE_NAME	"gwca0_rxts0"
> @@ -768,11 +769,13 @@ enum rswitch_gwca_mode {
>  #define GWARIRM_ARR		BIT(1)
>  
>  #define GWDCC_BALR		BIT(24)
> +#define GWDCC_DCP(prio)		(((prio) & 0x07) << 16)

I'd be glad to see defines for magic numbers above.

>  #define GWDCC_DQT		BIT(11)
>  #define GWDCC_ETS		BIT(9)
>  #define GWDCC_EDE		BIT(8)
>  
>  #define GWTRC(queue)		(GWTRC0 + (queue) / 32 * 4)
> +#define GWTPC_PPPL(ipv)		BIT(ipv)
>  #define GWDCC_OFFS(queue)	(GWDCC0 + (queue) * 4)
>  
>  #define GWDIS(i)		(GWDIS0 + (i) * 0x10)
> @@ -789,6 +792,8 @@ enum rswitch_gwca_mode {
>  #define CABPIRM_BPIOG		BIT(0)
>  #define CABPIRM_BPR		BIT(1)
>  
> +#define CABPPFLC_INIT_VALUE	0x00800080
> +
>  /* MFWD */
>  #define FWPC0_LTHTA		BIT(0)
>  #define FWPC0_IP4UE		BIT(3)
> @@ -863,6 +868,7 @@ enum DIE_DT {
>  
>  /* For transmission */
>  #define INFO1_TSUN(val)		((u64)(val) << 8ULL)
> +#define INFO1_IPV(prio)		((u64)(prio) << 28ULL)
>  #define INFO1_CSD0(index)	((u64)(index) << 32ULL)
>  #define INFO1_CSD1(index)	((u64)(index) << 40ULL)
>  #define INFO1_DV(port_vector)	((u64)(port_vector) << 48ULL)
> -- 
> 2.25.1
> 
>