Re: [PATCH v17 06/22] cxl: Support dpa initialization without a mailbox

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Tue, 24 Jun 2025 15:13:39 +0100
alejandro.lucero-palau@amd.com wrote:

> From: Alejandro Lucero <alucerop@amd.com>
> 
> Type3 relies on mailbox CXL_MBOX_OP_IDENTIFY command for initializing
> memdev state params which end up being used for DPA initialization.
> 
> Allow a Type2 driver to initialize DPA simply by giving the size of its
> volatile hardware partition.
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> º

?  Looks like an accidental degree symbol.

> ---
>  drivers/cxl/core/mbox.c | 17 +++++++++++++++++
Location make sense?   I'd like some reasoning text for that in the patch
description.  After all whole point is this isn't a mailbox thing!

Maybe moving add_part and this to somewhere more general makes sense?

>  include/cxl/cxl.h       |  1 +
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index d78f6039f997..d3b4ba5214d5 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -1284,6 +1284,23 @@ static void add_part(struct cxl_dpa_info *info, u64 start, u64 size, enum cxl_pa
>  	info->nr_partitions++;
>  }
>  
> +/**
> + * cxl_set_capacity: initialize dpa by a driver without a mailbox.
> + *
> + * @cxlds: pointer to cxl_dev_state
> + * @capacity: device volatile memory size
> + */
> +void cxl_set_capacity(struct cxl_dev_state *cxlds, u64 capacity)
> +{
> +	struct cxl_dpa_info range_info = {
> +		.size = capacity,
> +	};
> +
> +	add_part(&range_info, 0, capacity, CXL_PARTMODE_RAM);
> +	cxl_dpa_setup(cxlds, &range_info);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_set_capacity, "CXL");
> +
>  int cxl_mem_dpa_fetch(struct cxl_memdev_state *mds, struct cxl_dpa_info *info)
>  {
>  	struct cxl_dev_state *cxlds = &mds->cxlds;
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index 0810c18d7aef..4975ead488b4 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -231,4 +231,5 @@ struct cxl_dev_state *_devm_cxl_dev_state_create(struct device *dev,
>  int cxl_map_component_regs(const struct cxl_register_map *map,
>  			   struct cxl_component_regs *regs,
>  			   unsigned long map_mask);
> +void cxl_set_capacity(struct cxl_dev_state *cxlds, u64 capacity);
>  #endif /* __CXL_CXL_H__ */