Re: [RFC PATCH net-next v3 10/20] net: dsa: qca8k: add priority tweak to qca8337 switch

[Vladimir Oltean <olteanv@gmail.com>]

On Wed, May 05, 2021 at 12:29:04AM +0200, Ansuel Smith wrote:
> The port 5 of the ar8337 have some problem in flood condition. The
> original legacy driver had some specific buffer and priority settings
> for the different port suggested by the QCA switch team. Add this
> missing settings to improve switch stability under load condition.
> The packet priority tweak and the rx delay is specific to qca8337.
> Limit this changes to qca8337 as now we also support 8327 switch.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> ---
>  drivers/net/dsa/qca8k.c | 54 +++++++++++++++++++++++++++++++++++++++--
>  drivers/net/dsa/qca8k.h | 24 ++++++++++++++++++
>  2 files changed, 76 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
> index 17c6fd4afa7d..9e034c445085 100644
> --- a/drivers/net/dsa/qca8k.c
> +++ b/drivers/net/dsa/qca8k.c
> @@ -783,7 +783,12 @@ static int
>  qca8k_setup(struct dsa_switch *ds)
>  {
>  	struct qca8k_priv *priv = (struct qca8k_priv *)ds->priv;
> +	const struct qca8k_match_data *data;
>  	int ret, i;
> +	u32 mask;
> +
> +	/* get the switches ID from the compatible */
> +	data = of_device_get_match_data(priv->dev);
>  
>  	/* Make sure that port 0 is the cpu port */
>  	if (!dsa_is_cpu_port(ds, 0)) {
> @@ -889,6 +894,45 @@ qca8k_setup(struct dsa_switch *ds)
>  		}
>  	}
>  
> +	if (data->id == QCA8K_ID_QCA8337) {
> +		for (i = 0; i < QCA8K_NUM_PORTS; i++) {
> +			switch (i) {
> +			/* The 2 CPU port and port 5 requires some different
> +			 * priority than any other ports.
> +			 */
> +			case 0:
> +			case 5:
> +			case 6:
> +				mask = QCA8K_PORT_HOL_CTRL0_EG_PRI0(0x3) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PRI1(0x4) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PRI2(0x4) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PRI3(0x4) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PRI4(0x6) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PRI5(0x8) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PORT(0x1e);
> +				break;
> +			default:
> +				mask = QCA8K_PORT_HOL_CTRL0_EG_PRI0(0x3) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PRI1(0x4) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PRI2(0x6) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PRI3(0x8) |
> +					QCA8K_PORT_HOL_CTRL0_EG_PORT(0x19);
> +			}
> +			qca8k_write(priv, QCA8K_REG_PORT_HOL_CTRL0(i), mask);
> +
> +			mask = QCA8K_PORT_HOL_CTRL1_ING(0x6) |
> +			QCA8K_PORT_HOL_CTRL1_EG_PRI_BUF_EN |
> +			QCA8K_PORT_HOL_CTRL1_EG_PORT_BUF_EN |
> +			QCA8K_PORT_HOL_CTRL1_WRED_EN;
> +			qca8k_rmw(priv, QCA8K_REG_PORT_HOL_CTRL1(i),
> +				  QCA8K_PORT_HOL_CTRL1_ING_BUF |
> +				  QCA8K_PORT_HOL_CTRL1_EG_PRI_BUF_EN |
> +				  QCA8K_PORT_HOL_CTRL1_EG_PORT_BUF_EN |
> +				  QCA8K_PORT_HOL_CTRL1_WRED_EN,
> +				  mask);
> +		}

What is this actually doing and why is it needed?

> +	}
> +
>  	/* Setup our port MTUs to match power on defaults */
>  	for (i = 0; i < QCA8K_NUM_PORTS; i++)
>  		priv->port_mtu[i] = ETH_FRAME_LEN + ETH_FCS_LEN;
> @@ -909,9 +953,13 @@ static void
>  qca8k_phylink_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
>  			 const struct phylink_link_state *state)
>  {
> +	const struct qca8k_match_data *data;
>  	struct qca8k_priv *priv = ds->priv;
>  	u32 reg, val;
>  
> +	/* get the switches ID from the compatible */
> +	data = of_device_get_match_data(priv->dev);
> +
>  	switch (port) {
>  	case 0: /* 1st CPU port */
>  		if (state->interface != PHY_INTERFACE_MODE_RGMII &&
> @@ -962,8 +1010,10 @@ qca8k_phylink_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
>  			    QCA8K_PORT_PAD_RGMII_EN |
>  			    QCA8K_PORT_PAD_RGMII_TX_DELAY(QCA8K_MAX_DELAY) |
>  			    QCA8K_PORT_PAD_RGMII_RX_DELAY(QCA8K_MAX_DELAY));
> -		qca8k_write(priv, QCA8K_REG_PORT5_PAD_CTRL,
> -			    QCA8K_PORT_PAD_RGMII_RX_DELAY_EN);
> +		/* QCA8337 requires to set rgmii rx delay */
> +		if (data->id == QCA8K_ID_QCA8337)
> +			qca8k_write(priv, QCA8K_REG_PORT5_PAD_CTRL,
> +				    QCA8K_PORT_PAD_RGMII_RX_DELAY_EN);

Why are we looking at an RGMII delay change in a patch about "priority
tweaks"? This patch is very confusing.

>  		break;
>  	case PHY_INTERFACE_MODE_SGMII:
>  	case PHY_INTERFACE_MODE_1000BASEX:
> diff --git a/drivers/net/dsa/qca8k.h b/drivers/net/dsa/qca8k.h
> index 86e8d479c9f9..34c5522e7202 100644
> --- a/drivers/net/dsa/qca8k.h
> +++ b/drivers/net/dsa/qca8k.h
> @@ -166,6 +166,30 @@
>  #define   QCA8K_PORT_LOOKUP_STATE			GENMASK(18, 16)
>  #define   QCA8K_PORT_LOOKUP_LEARN			BIT(20)
>  
> +#define QCA8K_REG_PORT_HOL_CTRL0(_i)			(0x970 + (_i) * 0x8)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI0_BUF		GENMASK(3, 0)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI0(x)		((x) << 0)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI1_BUF		GENMASK(7, 4)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI1(x)		((x) << 4)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI2_BUF		GENMASK(11, 8)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI2(x)		((x) << 8)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI3_BUF		GENMASK(15, 12)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI3(x)		((x) << 12)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI4_BUF		GENMASK(19, 16)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI4(x)		((x) << 16)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI5_BUF		GENMASK(23, 20)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PRI5(x)		((x) << 20)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PORT_BUF		GENMASK(29, 24)
> +#define   QCA8K_PORT_HOL_CTRL0_EG_PORT(x)		((x) << 24)
> +
> +#define QCA8K_REG_PORT_HOL_CTRL1(_i)			(0x974 + (_i) * 0x8)
> +#define   QCA8K_PORT_HOL_CTRL1_ING_BUF			GENMASK(3, 0)
> +#define   QCA8K_PORT_HOL_CTRL1_ING(x)			((x) << 0)
> +#define   QCA8K_PORT_HOL_CTRL1_EG_PRI_BUF_EN		BIT(6)
> +#define   QCA8K_PORT_HOL_CTRL1_EG_PORT_BUF_EN		BIT(7)
> +#define   QCA8K_PORT_HOL_CTRL1_WRED_EN			BIT(8)
> +#define   QCA8K_PORT_HOL_CTRL1_EG_MIRROR_EN		BIT(16)
> +
>  /* Pkt edit registers */
>  #define QCA8K_EGRESS_VLAN(x)				(0x0c70 + (4 * (x / 2)))
>  
> -- 
> 2.30.2
>