linux-kernel - Re: [PATCH V7 3/4] PCI: vmd: Add vmd_device

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Date:   Fri, 28 Oct 2022 14:13:08 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     "David E. Box" <david.e.box@...ux.intel.com>
Cc:     nirmal.patel@...ux.intel.com, jonathan.derrick@...ux.dev,
        lorenzo.pieralisi@....com, hch@...radead.org, kw@...ux.com,
        robh@...nel.org, bhelgaas@...gle.com, michael.a.bottini@...el.com,
        rafael@...nel.org, me@...ityamohan.in, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V7 3/4] PCI: vmd: Add vmd_device_data

On Mon, Oct 24, 2022 at 05:44:10PM -0700, David E. Box wrote:
> Add vmd_device_data to allow adding additional info for driver data.

>  	{PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_VMD_9A0B),
> -		.driver_data = VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |
> -				VMD_FEAT_HAS_BUS_RESTRICTIONS |
> -				VMD_FEAT_OFFSET_FIRST_VECTOR,},
> +		(kernel_ulong_t)&(struct vmd_device_data) {
> +			.features = VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |
> +				    VMD_FEAT_HAS_BUS_RESTRICTIONS |
> +				    VMD_FEAT_OFFSET_FIRST_VECTOR,
> +		},
> +	},

It looks like these devices come in families where several device IDs
share the same features.  I think this would be more readable if you
defined each family outside this table and simply referenced the
family here.  E.g., you could do something like:

  static struct vmd_device_data vmd_v1 = {
    .features = VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |
		VMD_FEAT_HAS_BUS_RESTRICTIONS |
		VMD_FEAT_OFFSET_FIRST_VECTOR,
  };

  {PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_VMD_9A0B),
    .driver_data = (kernel_ulong_t) &vmd_v1,

Then you can add VMD_FEAT_BIOS_PM_QUIRK and the .ltr value in one place
instead of repeating it a half dozen times.

>  	{0,}
>  };
>  MODULE_DEVICE_TABLE(pci, vmd_ids);
> -- 
> 2.25.1
>