Re: [PATCH] cxl: Move port register setup to when first dport appear

[Dave Jiang <dave.jiang@intel.com>]

On 9/18/25 12:30 PM, Ira Weiny wrote:
> Dave Jiang wrote:
> 
> [snip]
> 
>>
>> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
>> index 76dd06d282df..416d45516d82 100644
>> --- a/drivers/cxl/core/port.c
>> +++ b/drivers/cxl/core/port.c
>> @@ -867,9 +867,7 @@ static int cxl_port_add(struct cxl_port *port,
>>  		if (rc)
>>  			return rc;
>>  
>> -		rc = cxl_port_setup_regs(port, component_reg_phys);
>> -		if (rc)
>> -			return rc;
>> +		port->component_reg_phys = component_reg_phys;
>>  	} else {
>>  		rc = dev_set_name(dev, "root%d", port->id);
>>  		if (rc)
>> @@ -1200,6 +1198,18 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
>>  
>>  	cxl_debugfs_create_dport_dir(dport);
>>  
>> +	/*
>> +	 * Setup port register if this is the first dport showed up. Having
>> +	 * a dport also means that there is at least 1 active link.
>> +	 */
>> +	if (port->nr_dports == 1 &&
>> +	    port->component_reg_phys != CXL_RESOURCE_NONE) {
> 
> Should this be
> 	    port->component_reg_phys == CXL_RESOURCE_NONE) {
> 	                             ^^
> ?
> 
> to match with 
> 
>         /* Note: endpoint port component registers are derived from @cxlds */
>         endpoint = devm_cxl_add_port(host, &cxlmd->dev, CXL_RESOURCE_NONE,
>                                      parent_dport);
> 
> in the memdev probe path?


No. port->component_reg_phys gets set in cxl_port_add(). So by the time the first dport shows up, we are using it to setup the register and then setting that back to CXL_RESOURCE_NONE. So therefore the port probe happens when it's the first dport and port->component_reg_phys is a valid address. 
 
> 
> Ira
> 
> [snip]