net: stmmac: fix CBS idleslope and sendslope calculation

When link speed is not 100 Mbps, port transmit rate and speed divider
are set to 8 and 1000000 respectively. These values are incorrect for
CBS idleslope and sendslope HW values calculation if the link speed is
not 1 Gbps.

This patch adds switch statement to set the values of port transmit rate
and speed divider for 10 Gbps, 5 Gbps, 2.5 Gbps, 1 Gbps, and 100 Mbps.
Note that CBS is not supported at 10 Mbps.

Fixes: bc41a66 ("net: stmmac: tc: Remove the speed dependency")
Fixes: 1f705bc ("net: stmmac: Add support for CBS QDISC")
Signed-off-by: Song, Yoong Siang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: yoongsiang2

drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c

@@ -316,6 +316,32 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
 	if (!priv->dma_cap.av)
 		return -EOPNOTSUPP;
 
+	/* Port Transmit Rate and Speed Divider */
+	switch (priv->speed) {
+	case SPEED_10000:
+		ptr = 32;
+		speed_div = 10000000;
+		break;
+	case SPEED_5000:
+		ptr = 32;
+		speed_div = 5000000;
+		break;
+	case SPEED_2500:
+		ptr = 8;
+		speed_div = 2500000;
+		break;
+	case SPEED_1000:
+		ptr = 8;
+		speed_div = 1000000;
+		break;
+	case SPEED_100:
+		ptr = 4;
+		speed_div = 100000;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
 	mode_to_use = priv->plat->tx_queues_cfg[queue].mode_to_use;
 	if (mode_to_use == MTL_QUEUE_DCB && qopt->enable) {
 		ret = stmmac_dma_qmode(priv, priv->ioaddr, queue, MTL_QUEUE_AVB);
@@ -332,10 +358,6 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
 		priv->plat->tx_queues_cfg[queue].mode_to_use = MTL_QUEUE_DCB;
 	}
 
-	/* Port Transmit Rate and Speed Divider */
-	ptr = (priv->speed == SPEED_100) ? 4 : 8;
-	speed_div = (priv->speed == SPEED_100) ? 100000 : 1000000;
-
 	/* Final adjustments for HW */
 	value = div_s64(qopt->idleslope * 1024ll * ptr, speed_div);
 	priv->plat->tx_queues_cfg[queue].idle_slope = value & GENMASK(31, 0);