Re: [PATCH 02/20] net: xilinx: tsn: add TSN endpoint wrapper driver

Hi,

On 8/9/2026 1:18 AM, Jakub Kicinski wrote:
> This is an AI-generated review of your patch. The human sending this
> email has considered the AI review valid, or at least plausible.
> ---
> net: xilinx: tsn: add TSN endpoint wrapper driver
>
> Adds a thin wrapper platform driver for the Xilinx TSN Endpoint Ethernet
> MAC IP node, along with a new Kconfig symbol and Makefile under
> drivers/net/ethernet/xilinx/tsn/. The wrapper enables the six IP-wide
> clocks and then populates the sub-nodes so each can bind to its own driver.
>
> A few questions below, all fairly minor.
>
>> diff --git a/drivers/net/ethernet/xilinx/tsn/Kconfig b/drivers/net/ethernet/xilinx/tsn/Kconfig
>> new file mode 100644
>> index 000000000000..45af4d3f10e6
>> --- /dev/null
>> +++ b/drivers/net/ethernet/xilinx/tsn/Kconfig
>> @@ -0,0 +1,15 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +#
>> +# Xilinx TSN device configuration
>> +#
>> +
>> +config XILINX_TSN
>> +	tristate "Xilinx TSN Ethernet driver"
>> +	depends on OF && HAS_IOMEM
> [Severity: Low]
> Should this depend on OF_ADDRESS rather than OF && HAS_IOMEM?
>
> The only functional statement in tsn_ip_probe() is:
>
> 	return devm_of_platform_populate(dev);
>
> and in include/linux/of_platform.h the real implementation is compiled
> only under CONFIG_OF_ADDRESS; otherwise the inline stub is:
>
> 	static inline int devm_of_platform_populate(struct device *dev)
> 	{
> 		return -ENODEV;
> 	}
>
> OF && HAS_IOMEM does not imply OF_ADDRESS, per drivers/of/Kconfig:
>
> 	config OF_ADDRESS
> 		def_bool y
> 		depends on !SPARC && (HAS_IOMEM || UML)
>
> sparc selects OF and provides HAS_IOMEM, and NET_VENDOR_XILINX has no
> architecture dependency, so XILINX_TSN is selectable there with
> OF_ADDRESS=n.
>
> In that configuration tsn_ip_probe() still runs devm_kzalloc(),
> devm_clk_bulk_get() and clk_bulk_prepare_enable() for all six clocks and
> registers the disable action, and then returns -ENODEV, so the driver can
> never bind and no sub-node device is created. The clocks are unwound by
> devres, so nothing leaks, but the whole driver is dead code in that
> configuration.
>
> This also stays as is through the end of the series, where the symbol is
> still "depends on OF && HAS_IOMEM" plus "depends on XILINX_DMA", and
> XILINX_DMA only has "depends on HAS_IOMEM".
>
>> +	help
>> +	  This driver supports the AMD/Xilinx Time-Sensitive Networking
>> +	  (TSN) Endpoint Ethernet MAC IP. It provides the wrapper device
>> +	  and the endpoint MAC that connects the IP to the host CPU. The
>> +	  three-port switch is supported by NET_DSA_XILINX_TSN.
> [Severity: Low]
> The help text describes "the endpoint MAC that connects the IP to the host
> CPU" and refers the reader to NET_DSA_XILINX_TSN, but at this commit the
> symbol only builds xilinx_tsn_main.o (clock enable plus
> devm_of_platform_populate()) and no NET_DSA_XILINX_TSN symbol exists in the
> tree yet.
>
> Both do appear later in the same series: the end-of-series Makefile has
>
> 	xilinx_tsn-y := xilinx_tsn_main.o xilinx_tsn_ep.o
>
> with &xlnx_tsn_ep_driver registered from xilinx_tsn_main.c, and
> NET_DSA_XILINX_TSN is added in drivers/net/dsa/xilinx/Kconfig.
>
> Since the text only appears in prose and not in a select or depends on,
> there is no build effect; would it be worth wording the help text so it
> matches what this commit actually builds, or is the forward reference
> intentional for the series?
>
>> +
>> +	  If unsure, say N.
> [ ... ]
>
>> diff --git a/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_main.c b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_main.c
>> new file mode 100644
>> index 000000000000..1ef1b0c2ee6e
>> --- /dev/null
>> +++ b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_main.c
>> @@ -0,0 +1,105 @@
> [ ... ]
>
>> +static int tsn_ip_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct xlnx_tsn_ip *w;
>> +	int ret;
>> +
>> +	w = devm_kzalloc(dev, sizeof(*w), GFP_KERNEL);
>> +	if (!w)
>> +		return -ENOMEM;
>> +
>> +	for (int i = 0; i < TSN_NUM_CLOCKS; i++)
>> +		w->clks[i].id = tsn_clk_names[i];
>> +
>> +	ret = devm_clk_bulk_get(dev, TSN_NUM_CLOCKS, w->clks);
>> +	if (ret)
>> +		return dev_err_probe(dev, ret, "failed to get clocks\n");
>> +
>> +	ret = clk_bulk_prepare_enable(TSN_NUM_CLOCKS, w->clks);
>> +	if (ret)
>> +		return dev_err_probe(dev, ret, "failed to enable clocks\n");
>> +
>> +	ret = devm_add_action_or_reset(dev, tsn_clk_bulk_disable, w);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return devm_of_platform_populate(dev);
>> +}
> [Severity: Low]
> Is there a consumer for xlnx,num-priorities anywhere?
>
> Documentation/devicetree/bindings/net/xlnx,tsn-endpoint-ethernet-mac.yaml
> lists it in the top-level required block for this same node:
>
> 	required:
> 	  - compatible
> 	  - reg
> 	  - clocks
> 	  - clock-names
> 	  - xlnx,num-priorities
> 	  - ranges
>
> tsn_ip_probe() is the only driver binding
> "xlnx,tsn-endpoint-ethernet-mac-3.0", and it only fills clks[].id and
> calls devm_clk_bulk_get(), clk_bulk_prepare_enable() and
> devm_of_platform_populate(). Grepping for num-priorities or
> num_priorities at the end of the series finds hits only inside the YAML
> itself plus unrelated fsl-mc and xe files.
>
> So device tree authors must supply the property to pass dt_binding_check
> while nothing reads it. Would it make sense to drop it from required
> until a driver actually uses it?
    yes, num-priorities has no user yet. But it's mandatory, and the driver
   should validate it against the TX channel count, which I missed. I'll add
   that in next version, read num-priorities at probe and bail out if it 
doesn't equal the
   number of TX channels.
I will address remaining  comments in next version.

Thanks
Srinivas Neeli
>
> [ ... ]