linux-kernel - Re: [PATCH v2 1/8] cxl/mem: Introduce a driver for CXL-2.0-Type-3 endpoints

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Date:   Wed, 10 Feb 2021 17:23:07 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Ben Widawsky <ben.widawsky@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-nvdimm@...ts.01.org>,
        <linux-pci@...r.kernel.org>, Bjorn Helgaas <helgaas@...nel.org>,
        "Chris Browy" <cbrowy@...ry-design.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Dan Williams" <dan.j.williams@...el.com>,
        David Hildenbrand <david@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Ira Weiny <ira.weiny@...el.com>,
        "Jon Masters" <jcm@...masters.org>,
        Rafael Wysocki <rafael.j.wysocki@...el.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Vishal Verma <vishal.l.verma@...el.com>,
        "John Groves (jgroves)" <jgroves@...ron.com>,
        "Kelley, Sean V" <sean.v.kelley@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Dave Jiang <dave.jiang@...el.com>
Subject: Re: [PATCH v2 1/8] cxl/mem: Introduce a driver for CXL-2.0-Type-3
 endpoints

On Wed, 10 Feb 2021 09:12:20 -0800
Ben Widawsky <ben.widawsky@...el.com> wrote:

...
   
> > > +}
> > > +
> > > +static int cxl_mem_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > > +{
> > > +	struct device *dev = &pdev->dev;
> > > +	int regloc;
> > > +
> > > +	regloc = cxl_mem_dvsec(pdev, PCI_DVSEC_ID_CXL_REGLOC_OFFSET);
> > > +	if (!regloc) {
> > > +		dev_err(dev, "register location dvsec not found\n");
> > > +		return -ENXIO;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static const struct pci_device_id cxl_mem_pci_tbl[] = {
> > > +	/* PCI class code for CXL.mem Type-3 Devices */
> > > +	{ PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> > > +	  PCI_CLASS_MEMORY_CXL << 8 | CXL_MEMORY_PROGIF, 0xffffff, 0 },  
> > 
> > Having looked at this and thought 'thats a bit tricky to check'
> > I did a quick grep and seems the kernel is split between this approach
> > and people going with the mor readable c99 style initiators
> > 	.class = .. etc
> > 
> > Personally I'd find the c99 approach easier to read. 
> >   
> 
> Well, it's Dan's patch, but I did modify this last. I took a look around, and
> the best fit seems to me seems to be:
> -       { PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> -         PCI_CLASS_MEMORY_CXL << 8 | CXL_MEMORY_PROGIF, 0xffffff, 0 },
> +       { PCI_DEVICE_CLASS((PCI_CLASS_MEMORY_CXL << 8 | CXL_MEMORY_PROGIF), ~0)},
> 
> That work for you?
> 

Yes that's definitely nicer.