[PATCH net-next 0/3] xgmac: Support for 16 MTL/DMA queues

[PATCH net-next 0/3] xgmac: Support for 16 MTL/DMA queues

[Jakub Raczynski]

New XGMAC datasheets for XGMAC 3.20a and 3.40a list support up to
16 MTL/DMA queues. This patch series does modifications to accommodate for
that, by following:
- Increase MAX value macros (this will increase memory allocation for driver)
- Add missing registers
- Modify/fix some functions to split TC and MTL/DMA

Biggest issue is that new hardware does support only 8 TC (traffic classes),
while supporting more MTL/DMA queues. This is problematic, as current code
does assume that these are equal which is not true anymore. Fix that by
applying better context to functions, using TC count read from HW_FEATURE
register where it applies.

For DMA/MTL queues higher than TC count redirect traffic to TC 0.
This is error in user configuration but quite possible to occur,
if user does 'one DMA/MTL queue per TC'.

This change has been tested on XGMAC based on 3.20a,
checked with 16 and 8 queue setup.

Jakub Raczynski (3):
  net/stmmac/dwxgmac: Modify DMA functions for future hardware
  net/stmmac/dwxgmac: Extend MTL/DMA support to 16 queues
  include/stmmac: Increase max DMA/MTL channel count from 8 to 16

 drivers/net/ethernet/stmicro/stmmac/common.h  |  1 +
 .../net/ethernet/stmicro/stmmac/dwxgmac2.h    |  2 +
 .../ethernet/stmicro/stmmac/dwxgmac2_core.c   | 58 ++++++++++++++++++-
 .../ethernet/stmicro/stmmac/dwxgmac2_dma.c    | 17 +++++-
 .../net/ethernet/stmicro/stmmac/stmmac_main.c |  5 +-
 include/linux/stmmac.h                        |  6 +-
 6 files changed, 80 insertions(+), 9 deletions(-)

-- 
2.34.1

[PATCH net-next 1/3] net/stmmac/dwxgmac: Modify DMA functions for future hardware

[Jakub Raczynski]

Datasheet for newer hardware of XGMAC (3.20a and 3.40a) list support for
up to 16 DMA/MTL queues. Currently maximum amount of queues in 8 set by
STMMAC_CH_MAX, MTL_MAX_TX_QUEUES, MTL_MAX_RX_QUEUES macros.
But before we set these to higher value there are changes to be made.

While newer hardware supports up to 16 MTL/DMA queues, there is support only
for 8 TC's (traffic control) entries. Current source assumes these are equal,
which might not be true. While in some cases it would be just incorrect value,
there are possible wrong memory accesses.

Fix this by saving number of TC supported by hardware in mac_device_info and
verify it in related functions. Also use TC count rather than MTL_MAX values
where it applies.

Signed-off-by: Jakub Raczynski <j.raczynski@samsung.com>
---
 drivers/net/ethernet/stmicro/stmmac/common.h    |  1 +
 .../net/ethernet/stmicro/stmmac/dwxgmac2_core.c | 17 ++++++++++++++++-
 .../net/ethernet/stmicro/stmmac/dwxgmac2_dma.c  | 14 ++++++++++++--
 .../net/ethernet/stmicro/stmmac/stmmac_main.c   |  5 ++++-
 4 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index 927ea6230073..c25ff649a847 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -630,6 +630,7 @@ struct mac_device_info {
 	unsigned int mcast_bits_log2;
 	unsigned int rx_csum;
 	unsigned int num_vlan;
+	u8 num_tc;
 	u32 vlan_filter[32];
 	bool vlan_fail_q_en;
 	u8 vlan_fail_q;
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
index f02b434bbd50..98b3e0cc84fa 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
@@ -102,6 +102,9 @@ static void dwxgmac2_rx_queue_prio(struct mac_device_info *hw, u32 prio,
 	u32 ctrl2, ctrl3;
 	int i;
 
+	if (WARN_ONCE(queue >= hw->num_tc, "invalid RX prio queue"))
+		return;
+
 	ctrl2 = readl(ioaddr + XGMAC_RXQ_CTRL2);
 	ctrl3 = readl(ioaddr + XGMAC_RXQ_CTRL3);
 
@@ -141,6 +144,9 @@ static void dwxgmac2_tx_queue_prio(struct mac_device_info *hw, u32 prio,
 	void __iomem *ioaddr = hw->pcsr;
 	u32 value, reg;
 
+	if (WARN_ONCE(queue >= hw->num_tc, "invalid TX prio queue"))
+		return;
+
 	reg = (queue < 4) ? XGMAC_TC_PRTY_MAP0 : XGMAC_TC_PRTY_MAP1;
 	if (queue >= 4)
 		queue -= 4;
@@ -233,7 +239,7 @@ static void dwxgmac2_prog_mtl_tx_algorithms(struct mac_device_info *hw,
 	writel(value, ioaddr + XGMAC_MTL_OPMODE);
 
 	/* Set ETS if desired */
-	for (i = 0; i < MTL_MAX_TX_QUEUES; i++) {
+	for (i = 0; i < hw->num_tc; i++) {
 		value = readl(ioaddr + XGMAC_MTL_TCx_ETS_CONTROL(i));
 		value &= ~XGMAC_TSA;
 		if (ets)
@@ -248,6 +254,9 @@ static void dwxgmac2_set_mtl_tx_queue_weight(struct stmmac_priv *priv,
 {
 	void __iomem *ioaddr = hw->pcsr;
 
+	if (WARN_ONCE(queue >= hw->num_tc, "invalid MTL TC queue"))
+		return;
+
 	writel(weight, ioaddr + XGMAC_MTL_TCx_QUANTUM_WEIGHT(queue));
 }
 
@@ -276,6 +285,9 @@ static void dwxgmac2_config_cbs(struct stmmac_priv *priv,
 	void __iomem *ioaddr = hw->pcsr;
 	u32 value;
 
+	if (WARN_ONCE(queue >= hw->num_tc, "invalid TC queue"))
+		return;
+
 	writel(send_slope, ioaddr + XGMAC_MTL_TCx_SENDSLOPE(queue));
 	writel(idle_slope, ioaddr + XGMAC_MTL_TCx_QUANTUM_WEIGHT(queue));
 	writel(high_credit, ioaddr + XGMAC_MTL_TCx_HICREDIT(queue));
@@ -366,6 +378,9 @@ static void dwxgmac2_flow_ctrl(struct mac_device_info *hw, unsigned int duplex,
 		for (i = 0; i < tx_cnt; i++) {
 			u32 value = XGMAC_TFE;
 
+			if (WARN_ONCE(i >= hw->num_tc, "invalid TC queue"))
+				break;
+
 			if (duplex)
 				value |= FIELD_PREP(XGMAC_PT, pause_time);
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
index 03437f1cf3df..6ac9e86f5faa 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
@@ -204,8 +204,18 @@ static void dwxgmac2_dma_tx_mode(struct stmmac_priv *priv, void __iomem *ioaddr,
 		value = u32_replace_bits(value, ttc, XGMAC_TTC);
 	}
 
-	/* Use static TC to Queue mapping */
-	value |= FIELD_PREP(XGMAC_Q2TCMAP, channel);
+	/* Newer XGMAC hardware does support up to 16 MTL/DMA queues but
+	 * only 8 traffic class queues. Redirect these, but this is error in
+	 * configuration.
+	 */
+	if (channel >= priv->hw->num_tc) {
+		dev_err(priv->device,
+			"Wrong channel set for TX mode, redirecting to TC 0\n");
+		value |= FIELD_PREP(XGMAC_Q2TCMAP, 0);
+	} else {
+		/* Use static TC to Queue mapping */
+		value |= FIELD_PREP(XGMAC_Q2TCMAP, channel);
+	}
 
 	if (qmode != MTL_QUEUE_AVB)
 		txqen = 0x2;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 3591755ea30b..a1ec3864009e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4140,7 +4140,7 @@ static int __stmmac_open(struct net_device *dev,
 	u8 chan;
 	int ret;
 
-	for (int i = 0; i < MTL_MAX_TX_QUEUES; i++)
+	for (int i = 0; i < priv->plat->tx_queues_to_use; i++)
 		if (priv->dma_conf.tx_queue[i].tbs & STMMAC_TBS_EN)
 			dma_conf->tx_queue[i].tbs = priv->dma_conf.tx_queue[i].tbs;
 	memcpy(&priv->dma_conf, dma_conf, sizeof(*dma_conf));
@@ -7443,6 +7443,9 @@ static int stmmac_hw_init(struct stmmac_priv *priv)
 		else
 			priv->plat->tx_coe = priv->dma_cap.tx_coe;
 
+		/* set number of traffic class queues */
+		priv->hw->num_tc = priv->dma_cap.numtc;
+
 		/* In case of GMAC4 rx_coe is from HW cap register. */
 		priv->plat->rx_coe = priv->dma_cap.rx_coe;
 
-- 
2.34.1

Re: [PATCH net-next 1/3] net/stmmac/dwxgmac: Modify DMA functions for future hardware

[Andrew Lunn]

On Mon, May 11, 2026 at 06:54:14PM +0200, Jakub Raczynski wrote:
> Datasheet for newer hardware of XGMAC (3.20a and 3.40a) list support for
> up to 16 DMA/MTL queues. Currently maximum amount of queues in 8 set by
> STMMAC_CH_MAX, MTL_MAX_TX_QUEUES, MTL_MAX_RX_QUEUES macros.
> But before we set these to higher value there are changes to be made.
> 
> While newer hardware supports up to 16 MTL/DMA queues, there is support only
> for 8 TC's (traffic control) entries. Current source assumes these are equal,
> which might not be true. While in some cases it would be just incorrect value,
> there are possible wrong memory accesses.
> 
> Fix this by saving number of TC supported by hardware in mac_device_info and
> verify it in related functions. Also use TC count rather than MTL_MAX values
> where it applies.
> +	/* Newer XGMAC hardware does support up to 16 MTL/DMA queues but
> +	 * only 8 traffic class queues. Redirect these, but this is error in
> +	 * configuration.
> +	 */

If this is an error in configuration why not return -EINVAL when the
configuration is requested?

	Andrew

Re: [PATCH net-next 1/3] net/stmmac/dwxgmac: Modify DMA functions for future hardware

[Jakub Raczynski]

[-- Attachment #1: Type: text/plain, Size: 1405 bytes --]

On Mon, May 11, 2026 at 08:02:14PM +0200, Andrew Lunn wrote:
> > +	/* Newer XGMAC hardware does support up to 16 MTL/DMA queues but
> > +	 * only 8 traffic class queues. Redirect these, but this is error in
> > +	 * configuration.
> > +	 */
> 
> If this is an error in configuration why not return -EINVAL when the
> configuration is requested?
> 
> 	Andrew
> 
Because is generally would not change a thing and would probably cause more
problems.

Parent function of stmmac_set_dma_operation_mode() -> stmmac_dma_tx_mode()
does not have any error handling. So we end up in situation where
tx_queues_to_use from DTS is still at its value, so we still have situation
where amount of DMA/MTL queueus is higher than number of TC's.

So then in case of XGMAC 3.20a/3.40a, we would have 8 DMA/MTL queues that
have assigned TC and 8 that don't. I cannot speak for older/other XGMAC if
there were ever a case like that where number of DMA/MTL != number of TC's.

So we will get many unusable MTL queues, eg. NAPI does use tx_queues_to_use in
its initialization, these queues will still be visible in system and can
be sent to. Leaving them unconfigured will very much likely lead to
'Tx queue timeout' and endless loop of interface restart via
stmmac_reset_subtask().

I think it is just simplier to leave warning that configuration is wrong,
handling error would be quite big change to make.

BR
Jakub Raczynski

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[PATCH net-next 2/3] net/stmmac/dwxgmac: Extend MTL/DMA support to 16 queues

[Jakub Raczynski]

New datasheets for XGMAC (3.20a and 3.40a, depending on product) support up to
16 MTL/DMA queues. Before we increase max amount through macro,
prepare dwxgmac functions to handle that.

Signed-off-by: Jakub Raczynski <j.raczynski@samsung.com>
---
 .../net/ethernet/stmicro/stmmac/dwxgmac2.h    |  2 ++
 .../ethernet/stmicro/stmmac/dwxgmac2_core.c   | 24 +++++++++++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
index 51943705a2b0..bd333afe7e1b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
@@ -257,6 +257,8 @@
 #define XGMAC_MTL_INT_STATUS		0x00001020
 #define XGMAC_MTL_RXQ_DMA_MAP0		0x00001030
 #define XGMAC_MTL_RXQ_DMA_MAP1		0x00001034
+#define XGMAC_MTL_RXQ_DMA_MAP2		0x00001038
+#define XGMAC_MTL_RXQ_DMA_MAP3		0x0000103c
 #define XGMAC_QxMDMACH(x)		GENMASK((x) * 8 + 7, (x) * 8)
 #define XGMAC_QxMDMACH_SHIFT(x)		((x) * 8)
 #define XGMAC_QDDMACH			BIT(7)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
index 98b3e0cc84fa..76f8214a6e5b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
@@ -266,9 +266,29 @@ static void dwxgmac2_map_mtl_to_dma(struct mac_device_info *hw, u32 queue,
 	void __iomem *ioaddr = hw->pcsr;
 	u32 value, reg;
 
-	reg = (queue < 4) ? XGMAC_MTL_RXQ_DMA_MAP0 : XGMAC_MTL_RXQ_DMA_MAP1;
-	if (queue >= 4)
+	switch (queue / 4) {
+	// queue 0 ~ 3
+	case 0:
+		reg = XGMAC_MTL_RXQ_DMA_MAP0;
+		break;
+	// queue 4 ~ 7
+	case 1:
+		reg = XGMAC_MTL_RXQ_DMA_MAP1;
 		queue -= 4;
+		break;
+	// queue 8 ~ 11
+	case 2:
+		reg = XGMAC_MTL_RXQ_DMA_MAP2;
+		queue -= 8;
+		break;
+	// queue 12 ~ 15
+	case 3:
+		reg = XGMAC_MTL_RXQ_DMA_MAP3;
+		queue -= 12;
+		break;
+	default:
+		return;
+	}
 
 	value = readl(ioaddr + reg);
 	value &= ~XGMAC_QxMDMACH(queue);
-- 
2.34.1

Re: [PATCH net-next 2/3] net/stmmac/dwxgmac: Extend MTL/DMA support to 16 queues

[Andrew Lunn]

On Mon, May 11, 2026 at 06:54:15PM +0200, Jakub Raczynski wrote:
> New datasheets for XGMAC (3.20a and 3.40a, depending on product) support up to
> 16 MTL/DMA queues. Before we increase max amount through macro,
> prepare dwxgmac functions to handle that.
> 
> Signed-off-by: Jakub Raczynski <j.raczynski@samsung.com>
> ---
>  .../net/ethernet/stmicro/stmmac/dwxgmac2.h    |  2 ++
>  .../ethernet/stmicro/stmmac/dwxgmac2_core.c   | 24 +++++++++++++++++--
>  2 files changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
> index 51943705a2b0..bd333afe7e1b 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
> @@ -257,6 +257,8 @@
>  #define XGMAC_MTL_INT_STATUS		0x00001020
>  #define XGMAC_MTL_RXQ_DMA_MAP0		0x00001030
>  #define XGMAC_MTL_RXQ_DMA_MAP1		0x00001034
> +#define XGMAC_MTL_RXQ_DMA_MAP2		0x00001038
> +#define XGMAC_MTL_RXQ_DMA_MAP3		0x0000103c
>  #define XGMAC_QxMDMACH(x)		GENMASK((x) * 8 + 7, (x) * 8)
>  #define XGMAC_QxMDMACH_SHIFT(x)		((x) * 8)
>  #define XGMAC_QDDMACH			BIT(7)
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> index 98b3e0cc84fa..76f8214a6e5b 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> @@ -266,9 +266,29 @@ static void dwxgmac2_map_mtl_to_dma(struct mac_device_info *hw, u32 queue,
>  	void __iomem *ioaddr = hw->pcsr;
>  	u32 value, reg;
>  
> -	reg = (queue < 4) ? XGMAC_MTL_RXQ_DMA_MAP0 : XGMAC_MTL_RXQ_DMA_MAP1;
> -	if (queue >= 4)
> +	switch (queue / 4) {
> +	// queue 0 ~ 3
> +	case 0:
> +		reg = XGMAC_MTL_RXQ_DMA_MAP0;
> +		break;
> +	// queue 4 ~ 7

I think

	switch (queue):
	case 0 ... 3:
	     reg = XGMAC_MTL_RXQ_DMA_MAP0;

is more readable, and expresses in code what you had in the comment.

   Andrew

Re: [PATCH net-next 2/3] net/stmmac/dwxgmac: Extend MTL/DMA support to 16 queues

[Jakub Raczynski]

[-- Attachment #1: Type: text/plain, Size: 278 bytes --]

On Mon, May 11, 2026 at 08:05:32PM +0200, Andrew Lunn wrote:
> 
> I think
> 
> 	switch (queue):
> 	case 0 ... 3:
> 	     reg = XGMAC_MTL_RXQ_DMA_MAP0;
> 
> is more readable, and expresses in code what you had in the comment.
> 
>    Andrew
>
Sure, can apply this in v2, thanks.

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[PATCH net-next 3/3] include/stmmac: Increase max DMA/MTL channel count from 8 to 16

[Jakub Raczynski]

Newer XGMAC hardware does support up to 16 DMA/MTL queues.
Add support for these after previous modifications of driver to accomodate for
that.

Signed-off-by: Jakub Raczynski <j.raczynski@samsung.com>
---
 include/linux/stmmac.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 4430b967abde..a9d19e2c388c 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -15,9 +15,9 @@
 #include <linux/platform_device.h>
 #include <linux/phylink.h>
 
-#define MTL_MAX_RX_QUEUES	8
-#define MTL_MAX_TX_QUEUES	8
-#define STMMAC_CH_MAX		8
+#define MTL_MAX_RX_QUEUES	16
+#define MTL_MAX_TX_QUEUES	16
+#define STMMAC_CH_MAX		16
 
 #define STMMAC_RX_COE_NONE	0
 #define STMMAC_RX_COE_TYPE1	1
-- 
2.34.1