[net-next v23 0/7] net: mtip: Add support for MTIP imx287 L2 switch driver

[net-next v23 0/7] net: mtip: Add support for MTIP imx287 L2 switch driver

[Lukasz Majewski]

This patch series adds support for More Than IP's L2 switch driver embedded
in some NXP's SoCs. This one has been tested on imx287, but is also available
in the vf610.

In the past there has been performed some attempts to upstream this driver:

1. The 4.19-cip based one [1]
2. DSA based one for 5.12 [2] - i.e. the switch itself was treat as a DSA switch
   with NO tag appended.
3. The extension for FEC driver for 5.12 [3] - the trick here was to fully reuse
   FEC when the in-HW switching is disabled. When bridge offloading is enabled,
   the driver uses already configured MAC and PHY to also configure PHY.

All three approaches were not accepted as eligible for upstreaming.

The driver from this series has following features:

1. It is fully separated from fec_main - i.e. can be used interchangeable
   with it. To be more specific - one can build them as modules and
   if required switch between them when e.g. bridge offloading is required.

   To be more specific:
        - Use FEC_MAIN: When one needs support for two ETH ports with separate
          uDMAs used for both and bridging can be realized in SW.

        - Use MTIPL2SW: When it is enough to support two ports with only uDMA0
          attached to switch and bridging shall be offloaded to HW. 

2. This driver uses MTIP's L2 switch internal VLAN feature to provide port
   separation at boot time. Port separation is disabled when bridging is
   required.

3. Example usage:
        Configuration:
        ip link set lan0 up; sleep 1;
        ip link set lan1 up; sleep 1;
        ip link add name br0 type bridge;
        ip link set br0 up; sleep 1;
        ip link set lan0 master br0;
        ip link set lan1 master br0;
        bridge link;
        ip addr add 192.168.2.17/24 dev br0;
        ping -c 5 192.168.2.222

        Removal:
        ip link set br0 down;
        ip link delete br0 type bridge;
        ip link set dev lan1 down
        ip link set dev lan0 down

4. Limitations:
        - Driver enables and disables switch operation with learning and ageing.
        - Missing is the advanced configuration (e.g. adding entries to FBD). This is
          on purpose, as up till now we didn't had consensus about how the driver
          shall be added to Linux.
          However, on top of this patch set the code with SWITCHDEV support (v6.6.
          PREEMPT_RT enabled) has been implemented in [4].

5. Clang build:
	make LLVM_SUFFIX=-19 LLVM=1 mrproper
	cp ./arch/arm/configs/mxs_defconfig .config
	make ARCH=arm LLVM_SUFFIX=-19 LLVM=1 W=1 menuconfig
	make ARCH=arm LLVM_SUFFIX=-19 LLVM=1 W=1 -j8 LOADADDR=0x40008000 uImage dtbs

        make LLVM_SUFFIX=-19 LLVM=1 mrproper
        make LLVM_SUFFIX=-19 LLVM=1 allmodconfig
        make LLVM_SUFFIX=-19 LLVM=1 W=1 drivers/net/ethernet/freescale/mtipsw/ | tee llvm_build.log
        make LLVM_SUFFIX=-19 LLVM=1 W=1 -j8 | tee llvm_build.log

6. Kernel compliance checks:
	make coccicheck MODE=report J=4 M=drivers/net/ethernet/freescale/mtipsw/
        make allmodconfig; ~/work/src/smatch/smatch_scripts/kchecker drivers/net/ethernet/freescale/mtipsw/

7. GCC:
        make mrproper
        make allmodconfig
        make W=1 drivers/net/ethernet/freescale/mtipsw/

        
        [source OE/Yocto SDK build environment]
        CROSS_COMPILE=arm-poky-linux-gnueabi- ARCH=arm make mrproper
        cp ./arch/arm/configs/mxs_defconfig .config
        CROSS_COMPILE=arm-poky-linux-gnueabi- ARCH=arm make menuconfig
        CROSS_COMPILE=arm-poky-linux-gnueabi- ARCH=arm make -j8 LOADADDR=0x40008000 uImage dtbs

8. DT_SCHEMA checks:
        source ~/.venv/bin/activate
        source /opt/poky/3.1.31/environment-setup-armv5e-poky-linux-gnueabi
        make dt_binding_check DT_SCHEMA_FILES=nxp,imx28-mtip-switch.yaml
        make CHECK_DTBS=y DT_SCHEMA_FILES=nxp,imx28-mtip-switch.yaml nxp/mxs/imx28-xea.dtb


Links:
[1] - https://github.com/lmajewski/linux-imx28-l2switch/commits/master
[2] - https://github.com/lmajewski/linux-imx28-l2switch/tree/imx28-v5.12-L2-upstream-RFC_v1
[3] - https://source.denx.de/linux/linux-imx28-l2switch/-/tree/imx28-v5.12-L2-upstream-switchdev-RFC_v1?ref_type=heads
[4] - https://github.com/lmajewski/linux-imx28-l2switch/commits/vf610-linux-6.6.y-mtipl2sw


Lukasz Majewski (7):
  dt-bindings: net: Add MTIP L2 switch description
  net: mtip: The L2 switch driver for imx287
  net: mtip: Add buffers management functions to the L2 switch driver
  net: mtip: Add net_device_ops functions to the L2 switch driver
  net: mtip: Add mtip_switch_{rx|tx} functions to the L2 switch driver
  net: mtip: Extend the L2 switch driver with management operations
  net: mtip: Extend the L2 switch driver for imx287 with bridge
    operations

 .../bindings/net/nxp,imx28-mtip-switch.yaml   |  150 ++
 MAINTAINERS                                   |    7 +
 drivers/net/ethernet/freescale/Kconfig        |    1 +
 drivers/net/ethernet/freescale/Makefile       |    1 +
 drivers/net/ethernet/freescale/mtipsw/Kconfig |   13 +
 .../net/ethernet/freescale/mtipsw/Makefile    |    4 +
 .../net/ethernet/freescale/mtipsw/mtipl2sw.c  | 2032 +++++++++++++++++
 .../net/ethernet/freescale/mtipsw/mtipl2sw.h  |  648 ++++++
 .../ethernet/freescale/mtipsw/mtipl2sw_br.c   |  138 ++
 .../ethernet/freescale/mtipsw/mtipl2sw_mgnt.c |  442 ++++
 10 files changed, 3436 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/nxp,imx28-mtip-switch.yaml
 create mode 100644 drivers/net/ethernet/freescale/mtipsw/Kconfig
 create mode 100644 drivers/net/ethernet/freescale/mtipsw/Makefile
 create mode 100644 drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c
 create mode 100644 drivers/net/ethernet/freescale/mtipsw/mtipl2sw.h
 create mode 100644 drivers/net/ethernet/freescale/mtipsw/mtipl2sw_br.c
 create mode 100644 drivers/net/ethernet/freescale/mtipsw/mtipl2sw_mgnt.c

-- 
2.39.5

Re: [net-next,v23,2/7] net: mtip: The L2 switch driver for imx287

[Jakub Kicinski]

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
net: mtip: The L2 switch driver for imx287

This patch provides support for More Than IP L2 switch embedded in the
imx287 SoC, a two port switch placed between uDMA[01] and MAC-NET[01]
for offloading network traffic.

> diff --git a/drivers/net/ethernet/freescale/mtipsw/Kconfig b/drivers/net/ethernet/freescale/mtipsw/Kconfig
> new file mode 100644
> index 000000000000..7767bd7c707b
> --- /dev/null
> +++ b/drivers/net/ethernet/freescale/mtipsw/Kconfig
> @@ -0,0 +1,13 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config FEC_MTIP_L2SW
> +	tristate "MoreThanIP L2 switch support to FEC driver"

This isn't a bug, but the vendor name formatting is inconsistent between
the description line ("MoreThanIP") and the help text below ("MoreThan
IP"). The vendor should be consistently named throughout the file.

> +	depends on OF
> +	depends on NET_SWITCHDEV
> +	depends on BRIDGE
> +	depends on SOC_IMX28 || COMPILE_TEST
> +	help
> +	  This enables support for the MoreThan IP L2 switch on i.MX
> +	  SoCs (e.g. iMX287). It offloads bridging to this IP block's

The SoC name "iMX287" should be "i.MX287" to match NXP's standard naming
convention used throughout the kernel for i.MX SoCs.

> diff --git a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c
> new file mode 100644
> index 000000000000..0a193a12e160
> --- /dev/null
> +++ b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c

[ ... ]

> +static void mtip_mgnt_timer(struct timer_list *t)
> +{
> +	struct switch_enet_private *fep = timer_container_of(fep, t,
> +							     timer_mgnt);

Does this code cause undefined behavior? The timer_container_of macro
expands to container_of(t, typeof(*fep), timer_mgnt), which dereferences
the uninitialized 'fep' variable in the typeof() expression. This is the
first statement in the function where 'fep' is being declared and assigned
simultaneously.

Looking at how other timer callbacks use this macro, shouldn't this be:

	struct switch_enet_private *fep = container_of(t,
		struct switch_enet_private, timer_mgnt);

This will cause a crash when the timer fires at the mod_timer() call site
in mtip_config_switch().

[ ... ]

> +static void mtip_switch_tx(struct switch_enet_private *fep)
> +{
> +}
> +
> +static int mtip_switch_rx(struct net_device *dev, int budget)
> +{
> +	return -ENOMEM;
> +}

Can the driver actually send or receive packets with these implementations?

Looking at the call chain:
  mtip_interrupt() schedules NAPI on RX interrupt ->
  mtip_rx_napi() calls mtip_switch_rx() ->
  mtip_switch_rx() always returns -ENOMEM

This means all receive interrupts are treated as out-of-memory conditions
and no packets are ever delivered to the network stack. Similarly,
mtip_switch_tx() is an empty stub that does nothing.

The commit message states "It can be used interchangeably with current
FEC driver" which suggests a functional driver, but the network interface
cannot actually send or receive packets. Should the commit message clarify
this is an incomplete implementation, or are these functions missing their
implementation?

[ ... ]

> +static int mtip_parse_of(struct switch_enet_private *fep,
> +			 struct device_node *np)
> +{
> +	struct device_node *p;
> +	unsigned int port_num;
> +	int ret = 0;
> +
> +	p = of_get_child_by_name(np, "ethernet-ports");
> +
> +	for_each_available_child_of_node_scoped(p, port) {
> +		if (of_property_read_u32(port, "reg", &port_num))
> +			continue;
> +
> +		if (!(port_num == 1 || port_num == 2)) {
> +			dev_err(&fep->pdev->dev,
> +				"%s: The switch supports up to %d ports!\n",
> +				__func__, SWITCH_EPORT_NUMBER);
> +			goto of_get_err;
> +		}
> +
> +		fep->n_ports = port_num;
> +		ret = of_get_mac_address(port, &fep->mac[port_num - 1][0]);
> +		if (ret)
> +			dev_dbg(&fep->pdev->dev,
> +				"of_get_mac_address(%pOF) failed (%d)!\n",
> +				port, ret);
> +
> +		ret = of_property_read_string(port, "label",
> +					      &fep->ndev_name[port_num - 1]);
> +		if (ret < 0) {
> +			dev_err(&fep->pdev->dev,
> +				"%s: Cannot get ethernet port name (%d)!\n",
> +				__func__, ret);
> +			goto of_get_err;
> +		}
> +
> +		ret = of_get_phy_mode(port, &fep->phy_interface[port_num - 1]);
> +		if (ret < 0) {
> +			dev_err(&fep->pdev->dev,
> +				"%s: Cannot get PHY mode (%d)!\n", __func__,
> +				ret);
> +			goto of_get_err;
> +		}
> +
> +		fep->phy_np[port_num - 1] = of_parse_phandle(port,
> +							     "phy-handle", 0);

Can this code leak OF node references?

If the first port (port_num=1) successfully obtains its PHY handle via
of_parse_phandle() and stores the reference in phy_np[0], but a
subsequent port fails during of_property_read_string() for the 'label'
property or of_get_phy_mode(), the error path jumps to of_get_err which
only releases the parent node 'p'. The PHY handle reference obtained for
the first port is never released.

The error path returns to mtip_sw_probe() which returns error without
calling mtip_parse_of_cleanup(), leaking the phy_np[0] reference. Note
that line 1191 correctly calls mtip_parse_of_cleanup(fep) before goto,
showing the cleanup is needed for these earlier error paths too.

> +		if (!fep->phy_np[port_num - 1]) {
> +			mtip_parse_of_cleanup(fep);
> +			dev_err(&fep->pdev->dev,
> +				"%s: PHY handle not defined!\n", __func__);
> +			ret = -ENODEV;
> +			goto of_get_err;
> +		}
> +	}
> +
> + of_get_err:
> +	of_node_put(p);
-- 
pw-bot: cr

Re: [net-next v23 2/7] net: mtip: The L2 switch driver for imx287

[Jakub Kicinski]

On Thu,  5 Feb 2026 00:21:30 +0100 Lukasz Majewski wrote:
> This patch series provides support for More Than IP L2 switch embedded
> in the imx287 SoC.
> 
> This is a two port switch (placed between uDMA[01] and MAC-NET[01]),
> which can be used for offloading the network traffic.
> 
> It can be used interchangeably with current FEC driver - to be more
> specific: one can use either of it, depending on the requirements.
> 
> The biggest difference is the usage of DMA - when FEC is used, separate
> DMAs are available for each ENET-MAC block.
> However, with switch enabled - only the DMA0 is used to send/receive data
> to/form switch (and then switch sends them to respecitive ports).
> 
> Signed-off-by: Lukasz Majewski <lukasz.majewski@mailbox.org>
> Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>

Transient build failure here:

drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c:1072:32: warning: variable ‘priv’ set but not used [-Wunused-but-set-variable]
 1072 |         struct mtip_ndev_priv *priv;
      |                                ^~~~

I sent out the AI code reviews while at it, without looking at them.
So please approach them with caution..

Re: [net-next v23 2/7] net: mtip: The L2 switch driver for imx287

[Łukasz Majewski]

Hi Jakub,

> On Thu,  5 Feb 2026 00:21:30 +0100 Lukasz Majewski wrote:
> > This patch series provides support for More Than IP L2 switch
> > embedded in the imx287 SoC.
> > 
> > This is a two port switch (placed between uDMA[01] and MAC-NET[01]),
> > which can be used for offloading the network traffic.
> > 
> > It can be used interchangeably with current FEC driver - to be more
> > specific: one can use either of it, depending on the requirements.
> > 
> > The biggest difference is the usage of DMA - when FEC is used,
> > separate DMAs are available for each ENET-MAC block.
> > However, with switch enabled - only the DMA0 is used to
> > send/receive data to/form switch (and then switch sends them to
> > respecitive ports).
> > 
> > Signed-off-by: Lukasz Majewski <lukasz.majewski@mailbox.org>
> > Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
> > Reviewed-by: Andrew Lunn <andrew@lunn.ch>  
> 
> Transient build failure here:
> 
> drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c:1072:32: warning:
> variable ‘priv’ set but not used [-Wunused-but-set-variable] 1072 |
>       struct mtip_ndev_priv *priv; |
> ^~~~
> 
> I sent out the AI code reviews while at it, without looking at them.
> So please approach them with caution..

IMHO, issues pointed with AI review have been at discussed and
(to my best knowledge) addressed.

Shall I prepare next version of this patch set?

-- 
Best regards,

Łukasz Majewski

Re: [net-next v23 2/7] net: mtip: The L2 switch driver for imx287

[Łukasz Majewski]

Hi Jakub,

> Hi Jakub,
> 
> > On Thu,  5 Feb 2026 00:21:30 +0100 Lukasz Majewski wrote:  
> > > This patch series provides support for More Than IP L2 switch
> > > embedded in the imx287 SoC.
> > > 
> > > This is a two port switch (placed between uDMA[01] and
> > > MAC-NET[01]), which can be used for offloading the network
> > > traffic.
> > > 
> > > It can be used interchangeably with current FEC driver - to be
> > > more specific: one can use either of it, depending on the
> > > requirements.
> > > 
> > > The biggest difference is the usage of DMA - when FEC is used,
> > > separate DMAs are available for each ENET-MAC block.
> > > However, with switch enabled - only the DMA0 is used to
> > > send/receive data to/form switch (and then switch sends them to
> > > respecitive ports).
> > > 
> > > Signed-off-by: Lukasz Majewski <lukasz.majewski@mailbox.org>
> > > Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
> > > Reviewed-by: Andrew Lunn <andrew@lunn.ch>    
> > 
> > Transient build failure here:
> > 
> > drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c:1072:32: warning:
> > variable ‘priv’ set but not used [-Wunused-but-set-variable] 1072 |
> >       struct mtip_ndev_priv *priv; |
> > ^~~~
> > 
> > I sent out the AI code reviews while at it, without looking at them.
> > So please approach them with caution..  
> 
> IMHO, issues pointed with AI review have been at discussed and
> (to my best knowledge) addressed.
> 
> Shall I prepare next version of this patch set?
> 

I'm a bit confused regarding the next steps for this driver.

There was no reply regarding my last question - and I don't know how I
shall proceed...

-- 
Best regards,

Łukasz Majewski

Re: [net-next v23 2/7] net: mtip: The L2 switch driver for imx287

[Jakub Kicinski]

On Mon, 16 Feb 2026 10:23:59 +0100 Łukasz Majewski wrote:
> > > Transient build failure here:
> > > 
> > > drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c:1072:32: warning:
> > > variable ‘priv’ set but not used [-Wunused-but-set-variable] 1072 |
> > >       struct mtip_ndev_priv *priv; |
> > > ^~~~
> > > 
> > > I sent out the AI code reviews while at it, without looking at them.
> > > So please approach them with caution..    
> > 
> > IMHO, issues pointed with AI review have been at discussed and
> > (to my best knowledge) addressed.
> > 
> > Shall I prepare next version of this patch set?
> 
> I'm a bit confused regarding the next steps for this driver.

1. This version didn't build, so it's out.
2. Take the AI review under consideration.
3. Address issues from 1+2.
4. Post v24

Well before posting: 

4a) wait for net-next to open up, it's close right now

> There was no reply regarding my last question - and I don't know how I
> shall proceed...

Hope above clarifies.

I strongly advise you to follow the ML so you have a better
understanding of the process.