Re: [PATCH v26 1/8] sfc: add cxl support

["Cheatham, Benjamin" <benjamin.cheatham@amd.com>]

On 4/23/2026 1:05 PM, alejandro.lucero-palau@amd.com wrote:
> From: Alejandro Lucero <alucerop@amd.com>
> 
> Add CXL initialization based on new CXL API for accel drivers and make
> it dependent on kernel CXL configuration.
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Acked-by: Edward Cree <ecree.xilinx@gmail.com>
> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>

Code looks good, just some notes on the copyright notices and a tiny nit. With the copyright fixed:

Reviewed-by: Ben Cheatham <benjamin.cheatham@amd.com>

[snip]

> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
> new file mode 100644
> index 000000000000..b7e8d85a43d3
> --- /dev/null
> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
> @@ -0,0 +1,52 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/****************************************************************************
> + *
> + * Driver for AMD network controllers and boards
> + * Copyright (C) 2025, Advanced Micro Devices, Inc.

I'm not a lawyer, but I'm pretty sure the year needs to be 2026 here.
> + */
> +
> +#include <linux/pci.h>
> +
> +#include "net_driver.h"
> +#include "efx_cxl.h"
> +
> +#define EFX_CTPIO_BUFFER_SIZE	SZ_256M
> +
> +int efx_cxl_init(struct efx_probe_data *probe_data)
> +{
> +	struct efx_nic *efx = &probe_data->efx;
> +	struct pci_dev *pci_dev = efx->pci_dev;
> +	struct efx_cxl *cxl;
> +	u16 dvsec;
> +
> +	probe_data->cxl_pio_initialised = false;
> +
> +	/* Is the device configured with and using CXL? */
> +	if (!pcie_is_cxl(pci_dev))
> +		return 0;
> +
> +	dvsec = pci_find_dvsec_capability(pci_dev, PCI_VENDOR_ID_CXL,
> +					  PCI_DVSEC_CXL_DEVICE);
> +	if (!dvsec) {
> +		pci_info(pci_dev, "CXL_DVSEC_PCIE_DEVICE capability not found\n");
> +		return 0;
> +	}
> +
> +	pci_dbg(pci_dev, "CXL_DVSEC_PCIE_DEVICE capability found\n");
> +
> +	/* Create a cxl_dev_state embedded in the cxl struct using cxl core api
> +	 * specifying no mbox available.
> +	 */
> +	cxl = devm_cxl_dev_state_create(&pci_dev->dev, CXL_DEVTYPE_DEVMEM,
> +					pci_get_dsn(pci_dev), dvsec,
> +					struct efx_cxl, cxlds, false);
> +
> +	if (!cxl)
> +		return -ENOMEM;
> +
> +	probe_data->cxl = cxl;
> +
> +	return 0;
> +}
> +
> +MODULE_IMPORT_NS("CXL");
> diff --git a/drivers/net/ethernet/sfc/efx_cxl.h b/drivers/net/ethernet/sfc/efx_cxl.h
> new file mode 100644
> index 000000000000..04e46278464d
> --- /dev/null
> +++ b/drivers/net/ethernet/sfc/efx_cxl.h
> @@ -0,0 +1,29 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/****************************************************************************
> + * Driver for AMD network controllers and boards
> + * Copyright (C) 2025, Advanced Micro Devices, Inc.

Same thing here.

> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published
> + * by the Free Software Foundation, incorporated herein by reference.
> + */
> +
> +#ifndef EFX_CXL_H
> +#define EFX_CXL_H
> +
> +#ifdef CONFIG_SFC_CXL
> +
> +#include <cxl/cxl.h>
> +
> +struct efx_probe_data;
> +
> +struct efx_cxl {
> +	struct cxl_dev_state cxlds;
> +	struct cxl_memdev *cxlmd;
> +};
> +
> +int efx_cxl_init(struct efx_probe_data *probe_data);
> +#else
> +static inline int efx_cxl_init(struct efx_probe_data *probe_data) { return 0; }
> +#endif
> +#endif
> diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
> index b98c259f672d..3964b2c56609 100644
> --- a/drivers/net/ethernet/sfc/net_driver.h
> +++ b/drivers/net/ethernet/sfc/net_driver.h
> @@ -1197,14 +1197,24 @@ struct efx_nic {
>  	atomic_t n_rx_noskb_drops;
>  };
>  
> +#ifdef CONFIG_SFC_CXL
> +struct efx_cxl;
> +#endif
> +
>  /**
>   * struct efx_probe_data - State after hardware probe
>   * @pci_dev: The PCI device
>   * @efx: Efx NIC details
> + * @cxl: details of related cxl objects
> + * @cxl_pio_initialised: cxl initialization outcome.

Tiny nit: The description of the variable should use the english spelling as well (i.e. initialisation).

>   */
>  struct efx_probe_data {
>  	struct pci_dev *pci_dev;
>  	struct efx_nic efx;
> +#ifdef CONFIG_SFC_CXL
> +	struct efx_cxl *cxl;
> +	bool cxl_pio_initialised;
> +#endif
>  };
>  
>  static inline struct efx_nic *efx_netdev_priv(struct net_device *dev)