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

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

On 6/27/25 09:43, Jonathan Cameron wrote:
> 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
>> ---
>>   drivers/cxl/core/mbox.c | 17 +++++++++++++++++
>>   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);
> I missed that this function can in general fail.  If that either can't occur
> here for some reason or we don't care if does, add a comment. Otherwise handle
> the error.


I do not think it should fail under a controlled type2 initialization, 
but as it can fail and maybe future changes will make it more likely, I 
will add checking the call result.


Thanks


>> +}
>> +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__ */