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Subject: Re: [PATCH V7 3/4] PCI: vmd: Add vmd_device_data
From:   "David E. Box" <david.e.box@linux.intel.com>
Reply-To: david.e.box@linux.intel.com
To:     Christoph Hellwig <hch@infradead.org>,
        Bjorn Helgaas <helgaas@kernel.org>
Cc:     nirmal.patel@linux.intel.com, jonathan.derrick@linux.dev,
        lorenzo.pieralisi@arm.com, kw@linux.com, robh@kernel.org,
        bhelgaas@google.com, michael.a.bottini@intel.com,
        rafael@kernel.org, me@adhityamohan.in, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Mon, 31 Oct 2022 08:40:49 -0700
In-Reply-To: <Y19zcYqxk7LcGQfG@infradead.org>
References: <20221025004411.2910026-4-david.e.box@linux.intel.com>
         <20221028191308.GA903098@bhelgaas> <Y19zcYqxk7LcGQfG@infradead.org>
Organization: David E. Box
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On Mon, 2022-10-31 at 00:04 -0700, Christoph Hellwig wrote:
> On Fri, Oct 28, 2022 at 02:13:08PM -0500, Bjorn Helgaas wrote:
> > 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.
> 
> I wonder why we need the ltr field at all.  For those that set it
> is always the same value, so it could just be a quirk flag to set it.

Yeah, this makes sense particularly since this isn't intended as a permanent
fix. I'll get rid of it.

> 
> Tat being said I think thegrouping makes a lot of sense, but I'd just
> do it with a #define for the set of common quirk flags.

Works for me. I'll create a VMD_FEATS_CLIENT group but I'll keep the ltr quirk
separate since future client systems won't be using it.

David