Subject: Re: [PATCH v2 02/15] cxl: add function for type2 cxl regs setup

From: Jonathan Cameron <[email-masked]>
Date: Sun, 4 Aug 2024 18:15:29 +0100

On Mon, 15 Jul 2024 18:28:22 +0100
[email-masked] wrote:

> From: Alejandro Lucero <[email-masked]>
> 
> Create a new function for a type2 device initialising the opaque
> cxl_dev_state struct regarding cxl regs setup and mapping.
> 
> Signed-off-by: Alejandro Lucero <[email-masked]>
> ---
>  drivers/cxl/pci.c                  | 28 ++++++++++++++++++++++++++++
>  drivers/net/ethernet/sfc/efx_cxl.c |  3 +++
>  include/linux/cxl_accel_mem.h      |  1 +
>  3 files changed, 32 insertions(+)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index e53646e9f2fb..b34d6259faf4 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -11,6 +11,7 @@
>  #include <linux/pci.h>
>  #include <linux/aer.h>
>  #include <linux/io.h>
> +#include <linux/cxl_accel_mem.h>
>  #include "cxlmem.h"
>  #include "cxlpci.h"
>  #include "cxl.h"
> @@ -521,6 +522,33 @@ static int cxl_pci_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
>  	return cxl_setup_regs(map);
>  }
>  
> +int cxl_pci_accel_setup_regs(struct pci_dev *pdev, struct cxl_dev_state *cxlds)
> +{
> +	struct cxl_register_map map;
> +	int rc;
> +
> +	rc = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_MEMDEV, &map);
> +	if (rc)
> +		return rc;
> +
> +	rc = cxl_map_device_regs(&map, &cxlds->regs.device_regs);
> +	if (rc)
> +		return rc;
> +
> +	rc = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_COMPONENT,
> +				&cxlds->reg_map);
> +	if (rc)
> +		dev_warn(&pdev->dev, "No component registers (%d)\n", rc);

Not fatal?  If we think it will happen on real devices, then dev_warn
is too strong.

> +
> +	rc = cxl_map_component_regs(&cxlds->reg_map, &cxlds->regs.component,
> +				    BIT(CXL_CM_CAP_CAP_ID_RAS));
> +	if (rc)
> +		dev_dbg(&pdev->dev, "Failed to map RAS capability.\n");

pci_err() or similar would make sense here as we have asked for something
that isn't happening. Specification says this is mandatory so
definitely smells like a fatal error to me.

> +
> +	return rc;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_pci_accel_setup_regs, CXL);
> +
>  static int cxl_pci_ras_unmask(struct pci_dev *pdev)
>  {
>  	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
> index 4554dd7cca76..10c4fb915278 100644
> --- a/drivers/net/ethernet/sfc/efx_cxl.c
> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
> @@ -47,6 +47,9 @@ void efx_cxl_init(struct efx_nic *efx)
>  
>  	res = DEFINE_RES_MEM_NAMED(0, EFX_CTPIO_BUFFER_SIZE, "ram");
>  	cxl_accel_set_resource(cxl->cxlds, res, CXL_ACCEL_RES_RAM);
> +
> +	if (cxl_pci_accel_setup_regs(pci_dev, cxl->cxlds))
> +		pci_info(pci_dev, "CXL accel setup regs failed");
Handle errors fully. That is report them  up to the caller.

>  }
>  
>  
> diff --git a/include/linux/cxl_accel_mem.h b/include/linux/cxl_accel_mem.h
> index daf46d41f59c..ca7af4a9cefc 100644
> --- a/include/linux/cxl_accel_mem.h
> +++ b/include/linux/cxl_accel_mem.h
> @@ -19,4 +19,5 @@ void cxl_accel_set_dvsec(cxl_accel_state *cxlds, u16 dvsec);
>  void cxl_accel_set_serial(cxl_accel_state *cxlds, u64 serial);
>  void cxl_accel_set_resource(struct cxl_dev_state *cxlds, struct resource res,
>  			    enum accel_resource);
> +int cxl_pci_accel_setup_regs(struct pci_dev *pdev, struct cxl_dev_state *cxlds);
>  #endif