netdev - Re: [PATCH v18 04/20] cxl: allow Type2 drivers to map cxl component regs

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Message-ID: <765f9f24-cb26-4eb6-9a44-b215c5ca2a6c@amd.com>
Date: Wed, 24 Sep 2025 09:25:51 +0100
From: Alejandro Lucero Palau <alucerop@....com>
To: Jonathan Cameron <jonathan.cameron@...wei.com>,
 alejandro.lucero-palau@....com
Cc: linux-cxl@...r.kernel.org, netdev@...r.kernel.org,
 dan.j.williams@...el.com, edward.cree@....com, davem@...emloft.net,
 kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com, dave.jiang@...el.com
Subject: Re: [PATCH v18 04/20] cxl: allow Type2 drivers to map cxl component
 regs


On 9/18/25 12:03, Jonathan Cameron wrote:
> On Thu, 18 Sep 2025 10:17:30 +0100
> alejandro.lucero-palau@....com wrote:
>
>> From: Alejandro Lucero <alucerop@....com>
>>
>> Export cxl core functions for a Type2 driver being able to discover and
>> map the device component registers.
>>
>> Use it in sfc driver cxl initialization.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@....com>
>> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
>> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
>> index 56d148318636..cdfbe546d8d8 100644
>> --- a/drivers/net/ethernet/sfc/efx_cxl.c
>> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
>> @@ -5,6 +5,7 @@
>>    * Copyright (C) 2025, Advanced Micro Devices, Inc.
>>    */
>>   
>> +#include <cxl/cxl.h>
>>   #include <cxl/pci.h>
>>   #include <linux/pci.h>
>>   
>> @@ -19,6 +20,7 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>>   	struct pci_dev *pci_dev = efx->pci_dev;
>>   	struct efx_cxl *cxl;
>>   	u16 dvsec;
>> +	int rc;
>>   
>>   	probe_data->cxl_pio_initialised = false;
>>   
>> @@ -45,6 +47,37 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>>   	if (!cxl)
>>   		return -ENOMEM;
>>   
>> +	rc = cxl_pci_setup_regs(pci_dev, CXL_REGLOC_RBI_COMPONENT,
>> +				&cxl->cxlds.reg_map);
>> +	if (rc) {
>> +		dev_err(&pci_dev->dev, "No component registers (err=%d)\n", rc);
>> +		return rc;
>> +	}
>> +
>> +	if (!cxl->cxlds.reg_map.component_map.hdm_decoder.valid) {
>> +		dev_err(&pci_dev->dev, "Expected HDM component register not found\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	if (!cxl->cxlds.reg_map.component_map.ras.valid)
>> +		return dev_err_probe(&pci_dev->dev, -ENODEV,
>> +				     "Expected RAS component register not found\n");
> Why the mix of dev_err() and dev_err_probe()?
> I'd prefer dev_err_probe() for all these, but we definitely don't
> want a mix.


I'll use dev_err_probe here and in following patches extending sfc cxl 
functionality.


>> +
>> +	rc = cxl_map_component_regs(&cxl->cxlds.reg_map,
>> +				    &cxl->cxlds.regs.component,
>> +				    BIT(CXL_CM_CAP_CAP_ID_RAS));
>> +	if (rc) {
>> +		dev_err(&pci_dev->dev, "Failed to map RAS capability.\n");
>> +		return rc;
>> +	}
>> +
>> +	/*
>> +	 * Set media ready explicitly as there are neither mailbox for checking
>> +	 * this state nor the CXL register involved, both not mandatory for
>> +	 * type2.
>> +	 */
>> +	cxl->cxlds.media_ready = true;
>> +
>>   	probe_data->cxl = cxl;
>>   
>>   	return 0;
>> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
>> index 13d448686189..3b9c8cb187a3 100644
>> --- a/include/cxl/cxl.h
>> +++ b/include/cxl/cxl.h
>> +/**
>> + * cxl_map_component_regs - map cxl component registers
>> + *
> Why 2 blank lines?


I'll fix it.


Thanks!


>
>> + *
>> + * @map: cxl register map to update with the mappings
>> + * @regs: cxl component registers to work with
>> + * @map_mask: cxl component regs to map
>> + *
>> + * Returns integer: success (0) or error (-ENOMEM)
>> + *
>> + * Made public for Type2 driver support.
>> + */
>> +int cxl_map_component_regs(const struct cxl_register_map *map,
>> +			   struct cxl_component_regs *regs,
>> +			   unsigned long map_mask);
>>   #endif /* __CXL_CXL_H__ */
> 		       struct cxl_register_map *map);
>