Re: [PATCH v14 02/22] sfc: add cxl support

[Alison Schofield <alison.schofield@intel.com>]

On Thu, Apr 17, 2025 at 10:29:05PM +0100, 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>
> ---
>  drivers/net/ethernet/sfc/Kconfig      |  9 +++++
>  drivers/net/ethernet/sfc/Makefile     |  1 +
>  drivers/net/ethernet/sfc/efx.c        | 15 +++++++-
>  drivers/net/ethernet/sfc/efx_cxl.c    | 55 +++++++++++++++++++++++++++
>  drivers/net/ethernet/sfc/efx_cxl.h    | 40 +++++++++++++++++++
>  drivers/net/ethernet/sfc/net_driver.h | 10 +++++
>  6 files changed, 129 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/net/ethernet/sfc/efx_cxl.c
>  create mode 100644 drivers/net/ethernet/sfc/efx_cxl.h
> 
> diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
> index c4c43434f314..979f2801e2a8 100644
> --- a/drivers/net/ethernet/sfc/Kconfig
> +++ b/drivers/net/ethernet/sfc/Kconfig
> @@ -66,6 +66,15 @@ config SFC_MCDI_LOGGING
>  	  Driver-Interface) commands and responses, allowing debugging of
>  	  driver/firmware interaction.  The tracing is actually enabled by
>  	  a sysfs file 'mcdi_logging' under the PCI device.
> +config SFC_CXL
> +	bool "Solarflare SFC9100-family CXL support"
> +	depends on SFC && CXL_BUS >= SFC
> +	default SFC
> +	help
> +	  This enables SFC CXL support if the kernel is configuring CXL for
> +	  using CTPIO with CXL.mem. The SFC device with CXL support and
> +	  with a CXL-aware firmware can be used for minimizing latencies
> +	  when sending through CTPIO.

SFC is a tristate, and this new bool SFC_CXL defaults to it.
default y seems more obvious and follows convention in this Kconfig
file.

CXL_BUS >= SFC tripped me up in my testing where I had CXL_BUS M
and SFC Y. Why is that not allowable?