netdev - Re: [PATCH v11 05/23] cxl: add function for type2 cxl regs setup

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Message-ID: <e0ec21cd-bc12-4fb8-b89b-1d293cd9ff96@amd.com>
Date: Tue, 11 Mar 2025 15:05:38 -0500
From: Ben Cheatham <benjamin.cheatham@....com>
To: <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>, <benjamin.cheatham@....com>
Subject: Re: [PATCH v11 05/23] cxl: add function for type2 cxl regs setup

On 3/10/25 4:03 PM, alejandro.lucero-palau@....com wrote:
> From: Alejandro Lucero <alucerop@....com>
> 
> Create a new function for a type2 device initialising
> cxl_dev_state struct regarding cxl regs setup and mapping.
> 
> Export the capabilities found for checking them against the
> expected ones by the driver.
> 
> Signed-off-by: Alejandro Lucero <alucerop@....com>
> ---
>  drivers/cxl/core/pci.c | 52 ++++++++++++++++++++++++++++++++++++++++++
>  include/cxl/cxl.h      |  5 ++++
>  2 files changed, 57 insertions(+)
> 
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 05399292209a..e48320e16a4f 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -1095,6 +1095,58 @@ int cxl_pci_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_pci_setup_regs, "CXL");
>  
> +static int cxl_pci_setup_memdev_regs(struct pci_dev *pdev,
> +				     struct cxl_dev_state *cxlds,
> +				     unsigned long *caps)
> +{
> +	struct cxl_register_map map;
> +	int rc;
> +
> +	rc = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_MEMDEV, &map, caps);
> +	/*
> +	 * This call can return -ENODEV if regs not found. This is not an error
> +	 * for Type2 since these regs are not mandatory. If they do exist then
> +	 * mapping them should not fail. If they should exist, it is with driver
> +	 * calling cxl_pci_check_caps where the problem should be found.
> +	 */
> +	if (rc == -ENODEV)
> +		return 0;
> +
> +	if (rc)
> +		return rc;
> +
> +	return cxl_map_device_regs(&map, &cxlds->regs.device_regs);
> +}

Nitpick: I think this function should be renamed to cxl_pci_accel_setup_memdev_regs(). The way I see it
this function is really just a helper function for cxl_pci_accel_setup_regs(), so the name should
probably match.

My other reason for this is that cxl_pci_probe() is doing almost doing the same thing for memdev register
setup, but with more stringent error checking. The name now makes me think that this function could be
reused there which I don't think is true.

Either way:
Reviewed-by: Ben Cheatham <benjamin.cheatham@....com>