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

[Alejandro Lucero Palau <alucerop@amd.com>]

On 5/8/25 01:33, Alison Schofield wrote:
> 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?
>
>

Not sure what you mean here. This means that if SFC can only be a module 
if CXL_BUS is a module and you want CXL with SFC.

You can have SFC as built-in in that case but without CXL support.