linux-kernel - Re: [PATCH V16 4/6] cxl/pci: Create PCI DOE mailbox's for memory devices

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Date:   Tue, 19 Jul 2022 17:16:37 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     ira.weiny@...el.com
Cc:     Dan Williams <dan.j.williams@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Lukas Wunner <lukas@...ner.de>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>,
        linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
        linux-pci@...r.kernel.org
Subject: Re: [PATCH V16 4/6] cxl/pci: Create PCI DOE mailbox's for memory
 devices

In subject, s/mailbox's/mailboxes/

On Tue, Jul 19, 2022 at 01:52:47PM -0700, ira.weiny@...el.com wrote:
> From: Ira Weiny <ira.weiny@...el.com>
> 
> DOE mailbox objects will be needed for various mailbox communications
> with each memory device.
> 
> Iterate each DOE mailbox capability and create PCI DOE mailbox objects
> as found.
> 
> It is not anticipated that this is the final resting place for the
> iteration of the DOE devices.  The support of switch ports will drive
> this code into the PCIe side.  In this imagined architecture the CXL
> port driver would then query into the PCI device for the DOE mailbox
> array.
> 
> For now creating the mailboxes in the CXL port is good enough for the
> endpoints.  Later PCIe ports will need to support this to support switch
> ports more generically.

> +static void devm_cxl_pci_create_doe(struct cxl_dev_state *cxlds)
> +{
> +	struct device *dev = cxlds->dev;
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +	u16 off = 0;
> +
> +	xa_init(&cxlds->doe_mbs);
> +	if (devm_add_action(&pdev->dev, cxl_pci_destroy_doe, &cxlds->doe_mbs)) {
> +		dev_err(dev, "Failed to create XArray for DOE's\n");

s/DOE's/DOEs/

> +		return;
> +	}
> +
> +	/*
> +	 * Mailbox creation is best effort.  Higher layers must determine if
> +	 * the lack of a mailbox for their protocol is a device failure or not.
> +	 */
> +	pci_doe_for_each_off(pdev, off) {
> +		struct pci_doe_mb *doe_mb;
> +
> +		doe_mb = pcim_doe_create_mb(pdev, off);
> +		if (IS_ERR(doe_mb)) {
> +			dev_err(dev, "Failed to create MB object for MB @ %x\n",

Maybe "%#x" to avoid ambiguity?  Also below.

> +				off);
> +			continue;
> +		}
> +
> +		if (xa_insert(&cxlds->doe_mbs, off, doe_mb, GFP_KERNEL)) {
> +			dev_err(dev, "xa_insert failed to insert MB @ %x\n",
> +				off);
> +			continue;
> +		}
> +
> +		dev_dbg(dev, "Created DOE mailbox @%x\n", off);
> +	}
> +}
> +
>  static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  {
>  	struct cxl_register_map map;
> @@ -434,6 +476,8 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  
>  	cxlds->component_reg_phys = cxl_regmap_to_base(pdev, &map);
>  
> +	devm_cxl_pci_create_doe(cxlds);
> +
>  	rc = cxl_pci_setup_mailbox(cxlds);
>  	if (rc)
>  		return rc;
> -- 
> 2.35.3
>