[PATCH net-next v6 0/5] net: dsa: yt921x: Add DCB/QoS support

[PATCH net-next v6 0/5] net: dsa: yt921x: Add DCB/QoS support

[David Yang]

This series add DCB/QoS support to the driver.

v5: https://lore.kernel.org/r/20260128215202.2244266-1-mmyangfl@gmail.com
  - fix xmit priority for tag driver
v4: https://lore.kernel.org/r/20260127020847.1482724-1-mmyangfl@gmail.com
  - change the color for DEI bit and add a comment for it
v3: https://lore.kernel.org/r/20260125001328.3784006-1-mmyangfl@gmail.com
  - fix port_del_dscp_prio()
  - split yt921x_chip_setup()
v2: https://lore.kernel.org/r/20260122194233.2777550-1-mmyangfl@gmail.com
  - make DCB support optional
  - refine with enum yt921x_app_selector
  - add missing dscp_prio_mapping_is_global
  - fix pcp support
v1: https://lore.kernel.org/r/20260119185935.2072685-1-mmyangfl@gmail.com
  - rebase

David Yang (5):
  net: dsa: tag_yt921x: clarify priority and code fields
  net: dsa: tag_yt921x: add priority support
  net: dsa: yt921x: Refactor VLAN awareness setting
  net: dsa: yt921x: Refactor yt921x_chip_setup()
  net: dsa: yt921x: Add DCB/QoS support

 drivers/net/dsa/Kconfig  |   1 +
 drivers/net/dsa/yt921x.c | 310 ++++++++++++++++++++++++++++++++++++---
 drivers/net/dsa/yt921x.h |  55 +++++--
 net/dsa/tag_yt921x.c     |  89 +++++++----
 4 files changed, 393 insertions(+), 62 deletions(-)

-- 
2.51.0

[PATCH net-next v6 1/5] net: dsa: tag_yt921x: clarify priority and code fields

[David Yang]

Packet priority is part of the tag, and the priority and code fields are
used by tx and rx. Make revisions to reflect the facts.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 net/dsa/tag_yt921x.c | 83 ++++++++++++++++++++++++++++----------------
 1 file changed, 53 insertions(+), 30 deletions(-)

diff --git a/net/dsa/tag_yt921x.c b/net/dsa/tag_yt921x.c
index 6bbfd42dc5df..098863d491ff 100644
--- a/net/dsa/tag_yt921x.c
+++ b/net/dsa/tag_yt921x.c
@@ -14,11 +14,14 @@
  *     are conflicts somewhere and/or you want to change it for some reason.
  * Tag:
  *   2: VLAN Tag
- *   2: Rx Port
+ *   2:
  *     15b: Rx Port Valid
  *     14b-11b: Rx Port
- *     10b-0b: Cmd?
- *   2: Tx Port(s)
+ *     10b-8b: Tx/Rx Priority
+ *     7b: Tx/Rx Code Valid
+ *     6b-1b: Tx/Rx Code
+ *     0b: ? (unset)
+ *   2:
  *     15b: Tx Port(s) Valid
  *     10b-0b: Tx Port(s) Mask
  */
@@ -33,18 +36,30 @@
 
 #define YT921X_TAG_PORT_EN		BIT(15)
 #define YT921X_TAG_RX_PORT_M		GENMASK(14, 11)
-#define YT921X_TAG_RX_CMD_M		GENMASK(10, 0)
-#define  YT921X_TAG_RX_CMD(x)			FIELD_PREP(YT921X_TAG_RX_CMD_M, (x))
-#define  YT921X_TAG_RX_CMD_FORWARDED		0x80
-#define  YT921X_TAG_RX_CMD_UNK_UCAST		0xb2
-#define  YT921X_TAG_RX_CMD_UNK_MCAST		0xb4
-#define YT921X_TAG_TX_PORTS		GENMASK(10, 0)
+#define YT921X_TAG_PRIO_M		GENMASK(10, 8)
+#define  YT921X_TAG_PRIO(x)			FIELD_PREP(YT921X_TAG_PRIO_M, (x))
+#define YT921X_TAG_CODE_EN		BIT(7)
+#define YT921X_TAG_CODE_M		GENMASK(6, 1)
+#define  YT921X_TAG_CODE(x)			FIELD_PREP(YT921X_TAG_CODE_M, (x))
+#define YT921X_TAG_TX_PORTS_M		GENMASK(10, 0)
+#define  YT921X_TAG_TX_PORTS(x)			FIELD_PREP(YT921X_TAG_TX_PORTS_M, (x))
+
+/* Incomplete. Some are configurable via RMA_CTRL_CPU_CODE, the meaning of
+ * others remains unknown.
+ */
+enum yt921x_tag_code {
+	YT921X_TAG_CODE_FORWARD = 0,
+	YT921X_TAG_CODE_UNK_UCAST = 0x19,
+	YT921X_TAG_CODE_UNK_MCAST = 0x1a,
+	YT921X_TAG_CODE_PORT_COPY = 0x1b,
+	YT921X_TAG_CODE_FDB_COPY = 0x1c,
+};
 
 static struct sk_buff *
 yt921x_tag_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	__be16 *tag;
-	u16 tx;
+	u16 ctrl;
 
 	skb_push(skb, YT921X_TAG_LEN);
 	dsa_alloc_etype_header(skb, YT921X_TAG_LEN);
@@ -55,9 +70,9 @@ yt921x_tag_xmit(struct sk_buff *skb, struct net_device *netdev)
 	/* VLAN tag unrelated when TX */
 	tag[1] = 0;
 	tag[2] = 0;
-	tx = FIELD_PREP(YT921X_TAG_TX_PORTS, dsa_xmit_port_mask(skb, netdev)) |
-	     YT921X_TAG_PORT_EN;
-	tag[3] = htons(tx);
+	ctrl = YT921X_TAG_TX_PORTS(dsa_xmit_port_mask(skb, netdev)) |
+	       YT921X_TAG_PORT_EN;
+	tag[3] = htons(ctrl);
 
 	return skb;
 }
@@ -67,7 +82,6 @@ yt921x_tag_rcv(struct sk_buff *skb, struct net_device *netdev)
 {
 	unsigned int port;
 	__be16 *tag;
-	u16 cmd;
 	u16 rx;
 
 	if (unlikely(!pskb_may_pull(skb, YT921X_TAG_LEN)))
@@ -98,23 +112,32 @@ yt921x_tag_rcv(struct sk_buff *skb, struct net_device *netdev)
 		return NULL;
 	}
 
-	cmd = FIELD_GET(YT921X_TAG_RX_CMD_M, rx);
-	switch (cmd) {
-	case YT921X_TAG_RX_CMD_FORWARDED:
-		/* Already forwarded by hardware */
-		dsa_default_offload_fwd_mark(skb);
-		break;
-	case YT921X_TAG_RX_CMD_UNK_UCAST:
-	case YT921X_TAG_RX_CMD_UNK_MCAST:
-		/* NOTE: hardware doesn't distinguish between TRAP (copy to CPU
-		 * only) and COPY (forward and copy to CPU). In order to perform
-		 * a soft switch, NEVER use COPY action in the switch driver.
-		 */
-		break;
-	default:
+	if (!(rx & YT921X_TAG_CODE_EN)) {
 		dev_warn_ratelimited(&netdev->dev,
-				     "Unexpected rx cmd 0x%02x\n", cmd);
-		break;
+				     "Tag code not enabled in rx packet\n");
+	} else {
+		u16 code = FIELD_GET(YT921X_TAG_CODE_M, rx);
+
+		switch (code) {
+		case YT921X_TAG_CODE_FORWARD:
+		case YT921X_TAG_CODE_PORT_COPY:
+		case YT921X_TAG_CODE_FDB_COPY:
+			/* Already forwarded by hardware */
+			dsa_default_offload_fwd_mark(skb);
+			break;
+		case YT921X_TAG_CODE_UNK_UCAST:
+		case YT921X_TAG_CODE_UNK_MCAST:
+			/* NOTE: hardware doesn't distinguish between TRAP (copy
+			 * to CPU only) and COPY (forward and copy to CPU). In
+			 * order to perform a soft switch, NEVER use COPY action
+			 * in the switch driver.
+			 */
+			break;
+		default:
+			dev_warn_ratelimited(&netdev->dev,
+					     "Unknown code 0x%02x\n", code);
+			break;
+		}
 	}
 
 	/* Remove YT921x tag and update checksum */
-- 
2.51.0

[PATCH net-next v6 2/5] net: dsa: tag_yt921x: add priority support

[David Yang]

Required by DCB/QoS support of the switch driver, since the rx packets
will have non-zero priorities.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 net/dsa/tag_yt921x.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/dsa/tag_yt921x.c b/net/dsa/tag_yt921x.c
index 098863d491ff..aefef8c770e3 100644
--- a/net/dsa/tag_yt921x.c
+++ b/net/dsa/tag_yt921x.c
@@ -69,7 +69,9 @@ yt921x_tag_xmit(struct sk_buff *skb, struct net_device *netdev)
 	tag[0] = htons(ETH_P_YT921X);
 	/* VLAN tag unrelated when TX */
 	tag[1] = 0;
-	tag[2] = 0;
+	ctrl = YT921X_TAG_CODE(YT921X_TAG_CODE_FORWARD) | YT921X_TAG_CODE_EN |
+	       YT921X_TAG_PRIO(skb->priority);
+	tag[2] = htons(ctrl);
 	ctrl = YT921X_TAG_TX_PORTS(dsa_xmit_port_mask(skb, netdev)) |
 	       YT921X_TAG_PORT_EN;
 	tag[3] = htons(ctrl);
@@ -112,6 +114,8 @@ yt921x_tag_rcv(struct sk_buff *skb, struct net_device *netdev)
 		return NULL;
 	}
 
+	skb->priority = FIELD_GET(YT921X_TAG_PRIO_M, rx);
+
 	if (!(rx & YT921X_TAG_CODE_EN)) {
 		dev_warn_ratelimited(&netdev->dev,
 				     "Tag code not enabled in rx packet\n");
-- 
2.51.0

[PATCH net-next v6 3/5] net: dsa: yt921x: Refactor VLAN awareness setting

[David Yang]

Create a helper function to centralize the logic for enabling and
disabling VLAN awareness on a port.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 drivers/net/dsa/yt921x.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/net/dsa/yt921x.c b/drivers/net/dsa/yt921x.c
index d82608154c4f..c2998b6ae535 100644
--- a/drivers/net/dsa/yt921x.c
+++ b/drivers/net/dsa/yt921x.c
@@ -1769,6 +1769,18 @@ yt921x_dsa_port_mdb_add(struct dsa_switch *ds, int port,
 	return res;
 }
 
+static int
+yt921x_vlan_aware_set(struct yt921x_priv *priv, int port, bool vlan_aware)
+{
+	u32 ctrl;
+
+	if (!vlan_aware)
+		ctrl = 0;
+	else
+		ctrl = YT921X_PORT_IGR_TPIDn_CTAG(0);
+	return yt921x_reg_write(priv, YT921X_PORTn_IGR_TPID(port), ctrl);
+}
+
 static int
 yt921x_port_set_pvid(struct yt921x_priv *priv, int port, u16 vid)
 {
@@ -1818,14 +1830,7 @@ yt921x_vlan_filtering(struct yt921x_priv *priv, int port, bool vlan_filtering)
 	if (res)
 		return res;
 
-	/* Turn on / off VLAN awareness */
-	mask = YT921X_PORT_IGR_TPIDn_CTAG_M;
-	if (!vlan_filtering)
-		ctrl = 0;
-	else
-		ctrl = YT921X_PORT_IGR_TPIDn_CTAG(0);
-	res = yt921x_reg_update_bits(priv, YT921X_PORTn_IGR_TPID(port),
-				     mask, ctrl);
+	res = yt921x_vlan_aware_set(priv, port, vlan_filtering);
 	if (res)
 		return res;
 
@@ -2022,8 +2027,7 @@ static int yt921x_userport_standalone(struct yt921x_priv *priv, int port)
 		return res;
 
 	/* Turn off VLAN awareness */
-	mask = YT921X_PORT_IGR_TPIDn_CTAG_M;
-	res = yt921x_reg_clear_bits(priv, YT921X_PORTn_IGR_TPID(port), mask);
+	res = yt921x_vlan_aware_set(priv, port, false);
 	if (res)
 		return res;
 
-- 
2.51.0

[PATCH net-next v6 4/5] net: dsa: yt921x: Refactor yt921x_chip_setup()

[David Yang]

yt921x_chip_setup() is already pretty long, and is going to become
longer. Split it into parts.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 drivers/net/dsa/yt921x.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/drivers/net/dsa/yt921x.c b/drivers/net/dsa/yt921x.c
index c2998b6ae535..3128fe97b50f 100644
--- a/drivers/net/dsa/yt921x.c
+++ b/drivers/net/dsa/yt921x.c
@@ -2903,7 +2903,7 @@ static int yt921x_chip_reset(struct yt921x_priv *priv)
 	return 0;
 }
 
-static int yt921x_chip_setup(struct yt921x_priv *priv)
+static int yt921x_chip_setup_dsa(struct yt921x_priv *priv)
 {
 	struct dsa_switch *ds = &priv->ds;
 	unsigned long cpu_ports_mask;
@@ -2921,16 +2921,6 @@ static int yt921x_chip_setup(struct yt921x_priv *priv)
 	if (res)
 		return res;
 
-	/* Enable and clear MIB */
-	res = yt921x_reg_set_bits(priv, YT921X_FUNC, YT921X_FUNC_MIB);
-	if (res)
-		return res;
-
-	ctrl = YT921X_MIB_CTRL_CLEAN | YT921X_MIB_CTRL_ALL_PORT;
-	res = yt921x_reg_write(priv, YT921X_MIB_CTRL, ctrl);
-	if (res)
-		return res;
-
 	/* Setup software switch */
 	ctrl = YT921X_CPU_COPY_TO_EXT_CPU;
 	res = yt921x_reg_write(priv, YT921X_CPU_COPY, ctrl);
@@ -2983,6 +2973,29 @@ static int yt921x_chip_setup(struct yt921x_priv *priv)
 	if (res)
 		return res;
 
+	return 0;
+}
+
+static int yt921x_chip_setup(struct yt921x_priv *priv)
+{
+	u32 ctrl;
+	int res;
+
+	ctrl = YT921X_FUNC_MIB;
+	res = yt921x_reg_set_bits(priv, YT921X_FUNC, ctrl);
+	if (res)
+		return res;
+
+	res = yt921x_chip_setup_dsa(priv);
+	if (res)
+		return res;
+
+	/* Clear MIB */
+	ctrl = YT921X_MIB_CTRL_CLEAN | YT921X_MIB_CTRL_ALL_PORT;
+	res = yt921x_reg_write(priv, YT921X_MIB_CTRL, ctrl);
+	if (res)
+		return res;
+
 	/* Miscellaneous */
 	res = yt921x_reg_set_bits(priv, YT921X_SENSOR, YT921X_SENSOR_TEMP);
 	if (res)
-- 
2.51.0

[PATCH net-next v6 5/5] net: dsa: yt921x: Add DCB/QoS support

[David Yang]

Set up global DSCP/PCP priority mappings and add related DCB methods.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 drivers/net/dsa/Kconfig  |   1 +
 drivers/net/dsa/yt921x.c | 253 ++++++++++++++++++++++++++++++++++++++-
 drivers/net/dsa/yt921x.h |  55 +++++++--
 3 files changed, 298 insertions(+), 11 deletions(-)

diff --git a/drivers/net/dsa/Kconfig b/drivers/net/dsa/Kconfig
index 7eb301fd987d..24c37cbf70d7 100644
--- a/drivers/net/dsa/Kconfig
+++ b/drivers/net/dsa/Kconfig
@@ -158,6 +158,7 @@ config NET_DSA_VITESSE_VSC73XX_PLATFORM
 config NET_DSA_YT921X
 	tristate "Motorcomm YT9215 ethernet switch chip support"
 	select NET_DSA_TAG_YT921X
+	select NET_IEEE8021Q_HELPERS if DCB
 	help
 	  This enables support for the Motorcomm YT9215 ethernet switch
 	  chip.
diff --git a/drivers/net/dsa/yt921x.c b/drivers/net/dsa/yt921x.c
index 3128fe97b50f..98e8915dd6c2 100644
--- a/drivers/net/dsa/yt921x.c
+++ b/drivers/net/dsa/yt921x.c
@@ -8,6 +8,7 @@
  * Copyright (c) 2025 David Yang
  */
 
+#include <linux/dcbnl.h>
 #include <linux/etherdevice.h>
 #include <linux/if_bridge.h>
 #include <linux/if_hsr.h>
@@ -18,8 +19,11 @@
 #include <linux/of.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
+#include <linux/sort.h>
 
 #include <net/dsa.h>
+#include <net/dscp.h>
+#include <net/ieee8021q.h>
 
 #include "yt921x.h"
 
@@ -1774,8 +1778,11 @@ yt921x_vlan_aware_set(struct yt921x_priv *priv, int port, bool vlan_aware)
 {
 	u32 ctrl;
 
+	/* Abuse SVLAN for PCP parsing without polluting the FDB - it just works
+	 * despite YT921X_VLAN_CTRL_SVLAN_EN never being set
+	 */
 	if (!vlan_aware)
-		ctrl = 0;
+		ctrl = YT921X_PORT_IGR_TPIDn_STAG(0);
 	else
 		ctrl = YT921X_PORT_IGR_TPIDn_CTAG(0);
 	return yt921x_reg_write(priv, YT921X_PORTn_IGR_TPID(port), ctrl);
@@ -2396,6 +2403,122 @@ yt921x_dsa_port_stp_state_set(struct dsa_switch *ds, int port, u8 state)
 			port, res);
 }
 
+static int __maybe_unused
+yt921x_dsa_port_get_default_prio(struct dsa_switch *ds, int port)
+{
+	struct yt921x_priv *priv = to_yt921x_priv(ds);
+	u32 val;
+	int res;
+
+	mutex_lock(&priv->reg_lock);
+	res = yt921x_reg_read(priv, YT921X_PORTn_QOS(port), &val);
+	mutex_unlock(&priv->reg_lock);
+
+	if (res)
+		return res;
+
+	return FIELD_GET(YT921X_PORT_QOS_PRIO_M, val);
+}
+
+static int __maybe_unused
+yt921x_dsa_port_set_default_prio(struct dsa_switch *ds, int port, u8 prio)
+{
+	struct yt921x_priv *priv = to_yt921x_priv(ds);
+	u32 mask;
+	u32 ctrl;
+	int res;
+
+	if (prio >= YT921X_PRIO_NUM)
+		return -EINVAL;
+
+	mutex_lock(&priv->reg_lock);
+	mask = YT921X_PORT_QOS_PRIO_M | YT921X_PORT_QOS_PRIO_EN;
+	ctrl = YT921X_PORT_QOS_PRIO(prio) | YT921X_PORT_QOS_PRIO_EN;
+	res = yt921x_reg_update_bits(priv, YT921X_PORTn_QOS(port), mask, ctrl);
+	mutex_unlock(&priv->reg_lock);
+
+	return res;
+}
+
+static int __maybe_unused appprios_cmp(const void *a, const void *b)
+{
+	return ((const u8 *)b)[1] - ((const u8 *)a)[1];
+}
+
+static int __maybe_unused
+yt921x_dsa_port_get_apptrust(struct dsa_switch *ds, int port, u8 *sel,
+			     int *nselp)
+{
+	struct yt921x_priv *priv = to_yt921x_priv(ds);
+	u8 appprios[2][2] = {};
+	int nsel;
+	u32 val;
+	int res;
+
+	mutex_lock(&priv->reg_lock);
+	res = yt921x_reg_read(priv, YT921X_PORTn_PRIO_ORD(port), &val);
+	mutex_unlock(&priv->reg_lock);
+
+	if (res)
+		return res;
+
+	appprios[0][0] = IEEE_8021QAZ_APP_SEL_DSCP;
+	appprios[0][1] = (val >> (3 * YT921X_APP_SEL_DSCP)) & 7;
+	appprios[1][0] = DCB_APP_SEL_PCP;
+	appprios[1][1] = (val >> (3 * YT921X_APP_SEL_CVLAN_PCP)) & 7;
+	sort(appprios, ARRAY_SIZE(appprios), sizeof(appprios[0]), appprios_cmp,
+	     NULL);
+
+	nsel = 0;
+	for (int i = 0; i < ARRAY_SIZE(appprios) && appprios[i][1]; i++) {
+		sel[nsel] = appprios[i][0];
+		nsel++;
+	}
+	*nselp = nsel;
+
+	return 0;
+}
+
+static int __maybe_unused
+yt921x_dsa_port_set_apptrust(struct dsa_switch *ds, int port, const u8 *sel,
+			     int nsel)
+{
+	struct yt921x_priv *priv = to_yt921x_priv(ds);
+	struct device *dev = to_device(priv);
+	u32 ctrl;
+	int res;
+
+	if (nsel > YT921X_APP_SEL_NUM)
+		return -EINVAL;
+
+	ctrl = 0;
+	for (int i = 0; i < nsel; i++) {
+		switch (sel[i]) {
+		case IEEE_8021QAZ_APP_SEL_DSCP:
+			ctrl |= YT921X_PORT_PRIO_ORD_APPm(YT921X_APP_SEL_DSCP,
+							  7 - i);
+			break;
+		case DCB_APP_SEL_PCP:
+			ctrl |= YT921X_PORT_PRIO_ORD_APPm(YT921X_APP_SEL_CVLAN_PCP,
+							  7 - i);
+			ctrl |= YT921X_PORT_PRIO_ORD_APPm(YT921X_APP_SEL_SVLAN_PCP,
+							  7 - i);
+			break;
+		default:
+			dev_err(dev,
+				"Invalid apptrust selector (at %d-th). Supported: dscp, pcp\n",
+				i + 1);
+			return -EOPNOTSUPP;
+		}
+	}
+
+	mutex_lock(&priv->reg_lock);
+	res = yt921x_reg_write(priv, YT921X_PORTn_PRIO_ORD(port), ctrl);
+	mutex_unlock(&priv->reg_lock);
+
+	return res;
+}
+
 static int yt921x_port_down(struct yt921x_priv *priv, int port)
 {
 	u32 mask;
@@ -2721,6 +2844,13 @@ static int yt921x_port_setup(struct yt921x_priv *priv, int port)
 	if (res)
 		return res;
 
+	/* Clear prio order (even if DCB is not enabled) to avoid unsolicited
+	 * priorities
+	 */
+	res = yt921x_reg_write(priv, YT921X_PORTn_PRIO_ORD(port), 0);
+	if (res)
+		return res;
+
 	if (dsa_is_cpu_port(ds, port)) {
 		/* Egress of CPU port is supposed to be completely controlled
 		 * via tagging, so set to oneway isolated (drop all packets
@@ -2764,6 +2894,66 @@ static int yt921x_dsa_port_setup(struct dsa_switch *ds, int port)
 	return res;
 }
 
+/* Not "port" - DSCP mapping is global */
+static int __maybe_unused
+yt921x_dsa_port_get_dscp_prio(struct dsa_switch *ds, int port, u8 dscp)
+{
+	struct yt921x_priv *priv = to_yt921x_priv(ds);
+	u32 val;
+	int res;
+
+	mutex_lock(&priv->reg_lock);
+	res = yt921x_reg_read(priv, YT921X_IPM_DSCPn(dscp), &val);
+	mutex_unlock(&priv->reg_lock);
+
+	if (res)
+		return res;
+
+	return FIELD_GET(YT921X_IPM_PRIO_M, val);
+}
+
+static int __maybe_unused
+yt921x_dsa_port_del_dscp_prio(struct dsa_switch *ds, int port, u8 dscp, u8 prio)
+{
+	struct yt921x_priv *priv = to_yt921x_priv(ds);
+	u32 val;
+	int res;
+
+	mutex_lock(&priv->reg_lock);
+	/* During a "dcb app replace" command, the new app table entry will be
+	 * added first, then the old one will be deleted. But the hardware only
+	 * supports one QoS class per DSCP value (duh), so if we blindly delete
+	 * the app table entry for this DSCP value, we end up deleting the
+	 * entry with the new priority. Avoid that by checking whether user
+	 * space wants to delete the priority which is currently configured, or
+	 * something else which is no longer current.
+	 */
+	res = yt921x_reg_read(priv, YT921X_IPM_DSCPn(dscp), &val);
+	if (!res && FIELD_GET(YT921X_IPM_PRIO_M, val) == prio)
+		res = yt921x_reg_write(priv, YT921X_IPM_DSCPn(dscp),
+				       YT921X_IPM_PRIO(IEEE8021Q_TT_BK));
+	mutex_unlock(&priv->reg_lock);
+
+	return res;
+}
+
+static int __maybe_unused
+yt921x_dsa_port_add_dscp_prio(struct dsa_switch *ds, int port, u8 dscp, u8 prio)
+{
+	struct yt921x_priv *priv = to_yt921x_priv(ds);
+	int res;
+
+	if (prio >= YT921X_PRIO_NUM)
+		return -EINVAL;
+
+	mutex_lock(&priv->reg_lock);
+	res = yt921x_reg_write(priv, YT921X_IPM_DSCPn(dscp),
+			       YT921X_IPM_PRIO(prio));
+	mutex_unlock(&priv->reg_lock);
+
+	return res;
+}
+
 static int yt921x_edata_wait(struct yt921x_priv *priv, u32 *valp)
 {
 	u32 val = YT921X_EDATA_DATA_IDLE;
@@ -2976,6 +3166,47 @@ static int yt921x_chip_setup_dsa(struct yt921x_priv *priv)
 	return 0;
 }
 
+static int __maybe_unused yt921x_chip_setup_qos(struct yt921x_priv *priv)
+{
+	u32 ctrl;
+	int res;
+
+	/* DSCP to internal priorities */
+	for (u8 dscp = 0; dscp < DSCP_MAX; dscp++) {
+		int prio = ietf_dscp_to_ieee8021q_tt(dscp);
+
+		if (prio < 0)
+			return prio;
+
+		res = yt921x_reg_write(priv, YT921X_IPM_DSCPn(dscp),
+				       YT921X_IPM_PRIO(prio));
+		if (res)
+			return res;
+	}
+
+	/* 802.1Q QoS to internal priorities */
+	for (u8 pcp = 0; pcp < 8; pcp++)
+		for (u8 dei = 0; dei < 2; dei++) {
+			ctrl = YT921X_IPM_PRIO(pcp);
+			if (dei)
+				/* "Red" almost means drop, so it's not that
+				 * useful. Note that tc police does not support
+				 * Three-Color very well
+				 */
+				ctrl |= YT921X_IPM_COLOR_YELLOW;
+
+			for (u8 svlan = 0; svlan < 2; svlan++) {
+				u32 reg = YT921X_IPM_PCPn(svlan, dei, pcp);
+
+				res = yt921x_reg_write(priv, reg, ctrl);
+				if (res)
+					return res;
+			}
+		}
+
+	return 0;
+}
+
 static int yt921x_chip_setup(struct yt921x_priv *priv)
 {
 	u32 ctrl;
@@ -2990,6 +3221,12 @@ static int yt921x_chip_setup(struct yt921x_priv *priv)
 	if (res)
 		return res;
 
+#if IS_ENABLED(CONFIG_DCB)
+	res = yt921x_chip_setup_qos(priv);
+	if (res)
+		return res;
+#endif
+
 	/* Clear MIB */
 	ctrl = YT921X_MIB_CTRL_CLEAN | YT921X_MIB_CTRL_ALL_PORT;
 	res = yt921x_reg_write(priv, YT921X_MIB_CTRL, ctrl);
@@ -3105,10 +3342,23 @@ static const struct dsa_switch_ops yt921x_dsa_switch_ops = {
 	.port_mst_state_set	= yt921x_dsa_port_mst_state_set,
 	.vlan_msti_set		= yt921x_dsa_vlan_msti_set,
 	.port_stp_state_set	= yt921x_dsa_port_stp_state_set,
+#if IS_ENABLED(CONFIG_DCB)
+	/* dcb */
+	.port_get_default_prio	= yt921x_dsa_port_get_default_prio,
+	.port_set_default_prio	= yt921x_dsa_port_set_default_prio,
+	.port_get_apptrust	= yt921x_dsa_port_get_apptrust,
+	.port_set_apptrust	= yt921x_dsa_port_set_apptrust,
+#endif
 	/* port */
 	.get_tag_protocol	= yt921x_dsa_get_tag_protocol,
 	.phylink_get_caps	= yt921x_dsa_phylink_get_caps,
 	.port_setup		= yt921x_dsa_port_setup,
+#if IS_ENABLED(CONFIG_DCB)
+	/* dscp */
+	.port_get_dscp_prio	= yt921x_dsa_port_get_dscp_prio,
+	.port_del_dscp_prio	= yt921x_dsa_port_del_dscp_prio,
+	.port_add_dscp_prio	= yt921x_dsa_port_add_dscp_prio,
+#endif
 	/* chip */
 	.setup			= yt921x_dsa_setup,
 };
@@ -3175,6 +3425,7 @@ static int yt921x_mdio_probe(struct mdio_device *mdiodev)
 	ds = &priv->ds;
 	ds->dev = dev;
 	ds->assisted_learning_on_cpu_port = true;
+	ds->dscp_prio_mapping_is_global = true;
 	ds->priv = priv;
 	ds->ops = &yt921x_dsa_switch_ops;
 	ds->ageing_time_min = 1 * 5000;
diff --git a/drivers/net/dsa/yt921x.h b/drivers/net/dsa/yt921x.h
index bacd4ccaa8e5..3f129b8d403f 100644
--- a/drivers/net/dsa/yt921x.h
+++ b/drivers/net/dsa/yt921x.h
@@ -269,6 +269,38 @@
 #define YT921X_TPID_EGRn(x)		(0x100300 + 4 * (x))	/* [0, 3] */
 #define  YT921X_TPID_EGR_TPID_M			GENMASK(15, 0)
 
+#define YT921X_IPM_DSCPn(n)		(0x180000 + 4 * (n))	/* Internal Priority Map */
+#define YT921X_IPM_PCPn(map, dei, pcp)	(0x180100 + 4 * (16 * (map) + 8 * (dei) + (pcp)))
+#define  YT921X_IPM_PRIO_M			GENMASK(4, 2)
+#define   YT921X_IPM_PRIO(x)				FIELD_PREP(YT921X_IPM_PRIO_M, (x))
+#define  YT921X_IPM_COLOR_M			GENMASK(1, 0)
+#define   YT921X_IPM_COLOR(x)				FIELD_PREP(YT921X_IPM_COLOR_M, (x))
+#define   YT921X_IPM_COLOR_GREEN			YT921X_IPM_COLOR(0)
+#define   YT921X_IPM_COLOR_YELLOW			YT921X_IPM_COLOR(1)
+#define   YT921X_IPM_COLOR_RED				YT921X_IPM_COLOR(2)
+#define YT921X_PORTn_QOS(port)		(0x180180 + 4 * (port))
+#define  YT921X_PORT_QOS_CVLAN_PRIO_MAP_ID	BIT(5)
+#define  YT921X_PORT_QOS_SVLAN_PRIO_MAP_ID	BIT(4)
+#define  YT921X_PORT_QOS_PRIO_M			GENMASK(3, 1)
+#define   YT921X_PORT_QOS_PRIO(x)			FIELD_PREP(YT921X_PORT_QOS_PRIO_M, (x))
+#define  YT921X_PORT_QOS_PRIO_EN		BIT(0)
+#define YT921X_PORTn_PRIO_ORD(port)	(0x180200 + 4 * (port))
+#define  YT921X_PORT_PRIO_ORD_APPm_M(m)		GENMASK(3 * (m) + 2, 3 * (m))
+#define   YT921X_PORT_PRIO_ORD_APPm(m, x)		((x) << (3 * (m)))	/* 0: disabled, except PORT_QOS_PRIO */
+
+enum yt921x_app_selector {
+	YT921X_APP_SEL_MAC_SA,
+	YT921X_APP_SEL_MAC_DA,
+	YT921X_APP_SEL_VID,
+	YT921X_APP_SEL_ACL,
+	YT921X_APP_SEL_DSCP,
+	YT921X_APP_SEL_CVLAN_PCP,
+	YT921X_APP_SEL_SVLAN_PCP,
+	/* The physical port, i.e. YT921X_PORT_QOS_PRIO */
+	YT921X_APP_SEL_PORT,
+	YT921X_APP_SEL_NUM
+};
+
 #define YT921X_VLAN_IGR_FILTER		0x180280
 #define  YT921X_VLAN_IGR_FILTER_PORTn_BYPASS_IGMP(port)	BIT((port) + 11)
 #define  YT921X_VLAN_IGR_FILTER_PORTn(port)	BIT(port)
@@ -337,7 +369,7 @@
 #define YT921X_FDB_OUT0			0x1804b0
 #define  YT921X_FDB_IO0_ADDR_HI4_M		GENMASK(31, 0)
 #define YT921X_FDB_OUT1			0x1804b4
-#define  YT921X_FDB_IO1_EGR_INT_PRI_EN		BIT(31)
+#define  YT921X_FDB_IO1_EGR_PRIO_EN		BIT(31)
 #define  YT921X_FDB_IO1_STATUS_M		GENMASK(30, 28)
 #define   YT921X_FDB_IO1_STATUS(x)			FIELD_PREP(YT921X_FDB_IO1_STATUS_M, (x))
 #define   YT921X_FDB_IO1_STATUS_INVALID			YT921X_FDB_IO1_STATUS(0)
@@ -356,9 +388,9 @@
 #define   YT921X_FDB_IO2_EGR_PORTS(x)			FIELD_PREP(YT921X_FDB_IO2_EGR_PORTS_M, (x))
 #define  YT921X_FDB_IO2_EGR_DROP		BIT(17)
 #define  YT921X_FDB_IO2_COPY_TO_CPU		BIT(16)
-#define  YT921X_FDB_IO2_IGR_INT_PRI_EN		BIT(15)
-#define  YT921X_FDB_IO2_INT_PRI_M		GENMASK(14, 12)
-#define   YT921X_FDB_IO2_INT_PRI(x)			FIELD_PREP(YT921X_FDB_IO2_INT_PRI_M, (x))
+#define  YT921X_FDB_IO2_IGR_PRIO_EN		BIT(15)
+#define  YT921X_FDB_IO2_PRIO_M			GENMASK(14, 12)
+#define   YT921X_FDB_IO2_PRIO(x)			FIELD_PREP(YT921X_FDB_IO2_PRIO_M, (x))
 #define  YT921X_FDB_IO2_NEW_VID_M		GENMASK(11, 0)
 #define   YT921X_FDB_IO2_NEW_VID(x)			FIELD_PREP(YT921X_FDB_IO2_NEW_VID_M, (x))
 #define YT921X_FILTER_UNK_UCAST		0x180508
@@ -406,8 +438,9 @@
 #define  YT921X_VLAN_CTRL_FID_M			GENMASK_ULL(34, 23)
 #define   YT921X_VLAN_CTRL_FID(x)			FIELD_PREP(YT921X_VLAN_CTRL_FID_M, (x))
 #define  YT921X_VLAN_CTRL_LEARN_DIS		BIT_ULL(22)
-#define  YT921X_VLAN_CTRL_INT_PRI_EN		BIT_ULL(21)
-#define  YT921X_VLAN_CTRL_INT_PRI_M		GENMASK_ULL(20, 18)
+#define  YT921X_VLAN_CTRL_PRIO_EN		BIT_ULL(21)
+#define  YT921X_VLAN_CTRL_PRIO_M		GENMASK_ULL(20, 18)
+#define   YT921X_VLAN_CTRL_PRIO(x)			FIELD_PREP(YT921X_VLAN_CTRL_PRIO_M, (x))
 #define  YT921X_VLAN_CTRL_PORTS_M		GENMASK_ULL(17, 7)
 #define   YT921X_VLAN_CTRL_PORTS(x)			FIELD_PREP(YT921X_VLAN_CTRL_PORTS_M, (x))
 #define  YT921X_VLAN_CTRL_PORTn(port)		BIT_ULL((port) + 7)
@@ -433,14 +466,14 @@
 #define  YT921X_LAG_HASH_SRC_PORT		BIT(0)
 
 #define YT921X_PORTn_VLAN_CTRL(port)	(0x230010 + 4 * (port))
-#define  YT921X_PORT_VLAN_CTRL_SVLAN_PRI_EN	BIT(31)
-#define  YT921X_PORT_VLAN_CTRL_CVLAN_PRI_EN	BIT(30)
+#define  YT921X_PORT_VLAN_CTRL_SVLAN_PRIO_EN	BIT(31)
+#define  YT921X_PORT_VLAN_CTRL_CVLAN_PRIO_EN	BIT(30)
 #define  YT921X_PORT_VLAN_CTRL_SVID_M		GENMASK(29, 18)
 #define   YT921X_PORT_VLAN_CTRL_SVID(x)			FIELD_PREP(YT921X_PORT_VLAN_CTRL_SVID_M, (x))
 #define  YT921X_PORT_VLAN_CTRL_CVID_M		GENMASK(17, 6)
 #define   YT921X_PORT_VLAN_CTRL_CVID(x)			FIELD_PREP(YT921X_PORT_VLAN_CTRL_CVID_M, (x))
-#define  YT921X_PORT_VLAN_CTRL_SVLAN_PRI_M	GENMASK(5, 3)
-#define  YT921X_PORT_VLAN_CTRL_CVLAN_PRI_M	GENMASK(2, 0)
+#define  YT921X_PORT_VLAN_CTRL_SVLAN_PRIO_M	GENMASK(5, 3)
+#define  YT921X_PORT_VLAN_CTRL_CVLAN_PRIO_M	GENMASK(2, 0)
 #define YT921X_PORTn_VLAN_CTRL1(port)	(0x230080 + 4 * (port))
 #define  YT921X_PORT_VLAN_CTRL1_VLAN_RANGE_EN	BIT(8)
 #define  YT921X_PORT_VLAN_CTRL1_VLAN_RANGE_PROFILE_ID_M	GENMASK(7, 4)
@@ -478,6 +511,8 @@ enum yt921x_fdb_entry_status {
 #define YT921X_LAG_NUM		2
 #define YT921X_LAG_PORT_NUM	4
 
+#define YT921X_PRIO_NUM	8
+
 #define YT9215_MAJOR	0x9002
 #define YT9218_MAJOR	0x9001
 
-- 
2.51.0

Re: [PATCH net-next v6 5/5] net: dsa: yt921x: Add DCB/QoS support

[Vladimir Oltean]

On Sat, Jan 31, 2026 at 10:18:51AM +0800, David Yang wrote:
> @@ -1774,8 +1778,11 @@ yt921x_vlan_aware_set(struct yt921x_priv *priv, int port, bool vlan_aware)
>  {
>  	u32 ctrl;
>  
> +	/* Abuse SVLAN for PCP parsing without polluting the FDB - it just works
> +	 * despite YT921X_VLAN_CTRL_SVLAN_EN never being set
> +	 */

Why "abuse" - what else does this setting affect? Does the port not
remain VLAN-unaware w.r.t. filtering/forwarding destinations?

How is the unused YT921X_VLAN_CTRL_PRIO_EN field from VLAN table entries
related to VLAN PCP parsing?

>  	if (!vlan_aware)
> -		ctrl = 0;
> +		ctrl = YT921X_PORT_IGR_TPIDn_STAG(0);
>  	else
>  		ctrl = YT921X_PORT_IGR_TPIDn_CTAG(0);
>  	return yt921x_reg_write(priv, YT921X_PORTn_IGR_TPID(port), ctrl);

Re: [PATCH net-next v6 5/5] net: dsa: yt921x: Add DCB/QoS support

[David Yang]

On Mon, Feb 2, 2026 at 9:10 PM Vladimir Oltean <olteanv@gmail.com> wrote:
>
> On Sat, Jan 31, 2026 at 10:18:51AM +0800, David Yang wrote:
> > @@ -1774,8 +1778,11 @@ yt921x_vlan_aware_set(struct yt921x_priv *priv, int port, bool vlan_aware)
> >  {
> >       u32 ctrl;
> >
> > +     /* Abuse SVLAN for PCP parsing without polluting the FDB - it just works
> > +      * despite YT921X_VLAN_CTRL_SVLAN_EN never being set
> > +      */
>
> Why "abuse" - what else does this setting affect? Does the port not
> remain VLAN-unaware w.r.t. filtering/forwarding destinations?
>

It does. Recognizing SVLAN without enabling SVLAN bit makes it ignore
VLAN tag, but somehow except for PCP. I guess the manufacturer never
expected such usage.

> How is the unused YT921X_VLAN_CTRL_PRIO_EN field from VLAN table entries
> related to VLAN PCP parsing?
>

It's another appsel APP_SEL_VID, using priority in PRIO_M instead.

Re: [PATCH net-next v6 0/5] net: dsa: yt921x: Add DCB/QoS support

[Vladimir Oltean]

On Sat, Jan 31, 2026 at 10:18:46AM +0800, David Yang wrote:
> This series add DCB/QoS support to the driver.
> 
> v5: https://lore.kernel.org/r/20260128215202.2244266-1-mmyangfl@gmail.com
>   - fix xmit priority for tag driver
> v4: https://lore.kernel.org/r/20260127020847.1482724-1-mmyangfl@gmail.com
>   - change the color for DEI bit and add a comment for it
> v3: https://lore.kernel.org/r/20260125001328.3784006-1-mmyangfl@gmail.com
>   - fix port_del_dscp_prio()
>   - split yt921x_chip_setup()
> v2: https://lore.kernel.org/r/20260122194233.2777550-1-mmyangfl@gmail.com
>   - make DCB support optional
>   - refine with enum yt921x_app_selector
>   - add missing dscp_prio_mapping_is_global
>   - fix pcp support
> v1: https://lore.kernel.org/r/20260119185935.2072685-1-mmyangfl@gmail.com
>   - rebase
> 
> David Yang (5):
>   net: dsa: tag_yt921x: clarify priority and code fields
>   net: dsa: tag_yt921x: add priority support
>   net: dsa: yt921x: Refactor VLAN awareness setting
>   net: dsa: yt921x: Refactor yt921x_chip_setup()
>   net: dsa: yt921x: Add DCB/QoS support
> 
>  drivers/net/dsa/Kconfig  |   1 +
>  drivers/net/dsa/yt921x.c | 310 ++++++++++++++++++++++++++++++++++++---
>  drivers/net/dsa/yt921x.h |  55 +++++--
>  net/dsa/tag_yt921x.c     |  89 +++++++----
>  4 files changed, 393 insertions(+), 62 deletions(-)
> 
> -- 
> 2.51.0
> 

From the perspective of API use this appears fine.

Reviewed-by: Vladimir Oltean <olteanv@gmail.com>

Re: [PATCH net-next v6 0/5] net: dsa: yt921x: Add DCB/QoS support

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Sat, 31 Jan 2026 10:18:46 +0800 you wrote:
> This series add DCB/QoS support to the driver.
> 
> v5: https://lore.kernel.org/r/20260128215202.2244266-1-mmyangfl@gmail.com
>   - fix xmit priority for tag driver
> v4: https://lore.kernel.org/r/20260127020847.1482724-1-mmyangfl@gmail.com
>   - change the color for DEI bit and add a comment for it
> v3: https://lore.kernel.org/r/20260125001328.3784006-1-mmyangfl@gmail.com
>   - fix port_del_dscp_prio()
>   - split yt921x_chip_setup()
> v2: https://lore.kernel.org/r/20260122194233.2777550-1-mmyangfl@gmail.com
>   - make DCB support optional
>   - refine with enum yt921x_app_selector
>   - add missing dscp_prio_mapping_is_global
>   - fix pcp support
> v1: https://lore.kernel.org/r/20260119185935.2072685-1-mmyangfl@gmail.com
>   - rebase
> 
> [...]

Here is the summary with links:
  - [net-next,v6,1/5] net: dsa: tag_yt921x: clarify priority and code fields
    https://git.kernel.org/netdev/net-next/c/a63daf73a587
  - [net-next,v6,2/5] net: dsa: tag_yt921x: add priority support
    https://git.kernel.org/netdev/net-next/c/8cdb2cc9a11b
  - [net-next,v6,3/5] net: dsa: yt921x: Refactor VLAN awareness setting
    https://git.kernel.org/netdev/net-next/c/75b85703fd48
  - [net-next,v6,4/5] net: dsa: yt921x: Refactor yt921x_chip_setup()
    https://git.kernel.org/netdev/net-next/c/95e6bcab3c08
  - [net-next,v6,5/5] net: dsa: yt921x: Add DCB/QoS support
    https://git.kernel.org/netdev/net-next/c/d5f778353fd4

You are awesome, thank you!
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