linux-kernel - Re: [PATCH v6 12/27] cxl/regs: Remove early capability checks in Component Register setup

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Message-ID: <a451d410-4acb-8d79-36ed-da14bfd5a9c6@intel.com>
Date:   Thu, 22 Jun 2023 16:48:06 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Terry Bowman <terry.bowman@....com>, <alison.schofield@...el.com>,
        <vishal.l.verma@...el.com>, <ira.weiny@...el.com>,
        <bwidawsk@...nel.org>, <dan.j.williams@...el.com>,
        <Jonathan.Cameron@...wei.com>, <linux-cxl@...r.kernel.org>
CC:     <rrichter@....com>, <linux-kernel@...r.kernel.org>,
        <bhelgaas@...gle.com>
Subject: Re: [PATCH v6 12/27] cxl/regs: Remove early capability checks in
 Component Register setup



On 6/21/23 20:51, Terry Bowman wrote:
> From: Robert Richter <rrichter@....com>
> 
> When probing the Component Registers in function cxl_probe_regs()
> there are also checks for the existence of the HDM and RAS
> capabilities. The checks may fail for components that do not implement
> the HDM capability causing the Component Registers setup to fail too.
> 
> Remove the checks for a generalized use of cxl_probe_regs() and check
> them directly before mapping the RAS or HDM capabilities. This allows
> it to setup other Component Registers esp. of an RCH Downstream Port,
> which will be implemented in a follow-on patch.
> 
> Signed-off-by: Robert Richter <rrichter@....com>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
>   drivers/cxl/core/regs.c | 8 --------
>   drivers/cxl/pci.c       | 2 ++
>   drivers/cxl/port.c      | 5 ++++-
>   3 files changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
> index e035ad8827a4..e68848075bb6 100644
> --- a/drivers/cxl/core/regs.c
> +++ b/drivers/cxl/core/regs.c
> @@ -369,14 +369,6 @@ static int cxl_probe_regs(struct cxl_register_map *map)
>   	case CXL_REGLOC_RBI_COMPONENT:
>   		comp_map = &map->component_map;
>   		cxl_probe_component_regs(dev, base, comp_map);
> -		if (!comp_map->hdm_decoder.valid) {
> -			dev_err(dev, "HDM decoder registers not found\n");
> -			return -ENXIO;
> -		}
> -
> -		if (!comp_map->ras.valid)
> -			dev_dbg(dev, "RAS registers not found\n");
> -
>   		dev_dbg(dev, "Set up component registers\n");
>   		break;
>   	case CXL_REGLOC_RBI_MEMDEV:
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index ac17bc0430dc..945ca0304d68 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -630,6 +630,8 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>   	rc = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_COMPONENT, &map);
>   	if (rc)
>   		dev_warn(&pdev->dev, "No component registers (%d)\n", rc);
> +	else if (!map.component_map.ras.valid)
> +		dev_dbg(&pdev->dev, "RAS registers not found\n");
>   
>   	cxlds->component_reg_phys = map.resource;
>   
> diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
> index 4cef2bf45ad2..01e84ea54f56 100644
> --- a/drivers/cxl/port.c
> +++ b/drivers/cxl/port.c
> @@ -102,8 +102,11 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
>   		return rc;
>   
>   	cxlhdm = devm_cxl_setup_hdm(port, &info);
> -	if (IS_ERR(cxlhdm))
> +	if (IS_ERR(cxlhdm)) {
> +		if (PTR_ERR(cxlhdm) == -ENODEV)
> +			dev_err(&port->dev, "HDM decoder registers not found\n");
>   		return PTR_ERR(cxlhdm);
> +	}
>   
>   	/* Cache the data early to ensure is_visible() works */
>   	read_cdat_data(port);