Re: [PATCH 1/5] PCI: Recognize Thunderbolt devices

From: Lukas Wunner <lukas@wunner.de>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: dri-devel@lists.freedesktop.org,
	Michael Jamet <michael.jamet@intel.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	linux-pci@vger.kernel.org, Darren Hart <dvhart@infradead.org>,
	Andy Shevchenko <andy@infradead.org>,
	platform-driver-x86@vger.kernel.org,
	Ben Skeggs <bskeggs@redhat.com>,
	nouveau@lists.freedesktop.org,
	Alex Deucher <alexander.deucher@amd.com>,
	Christian Koenig <christian.koenig@amd.com>,
	amd-gfx@lists.freedesktop.org, Peter Wu <peter@lekensteyn.nl>
Subject: Re: [PATCH 1/5] PCI: Recognize Thunderbolt devices
Date: Sat, 25 Feb 2017 08:40:03 +0100	[thread overview]
Message-ID: <20170225074003.GA905@wunner.de> (raw)
In-Reply-To: <20170224221724.GA26430@bhelgaas-glaptop.roam.corp.google.com>

On Fri, Feb 24, 2017 at 04:17:24PM -0600, Bjorn Helgaas wrote:
> On Fri, Feb 24, 2017 at 08:19:45PM +0100, Lukas Wunner wrote:
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -358,6 +358,7 @@ struct pci_dev {
> >  	unsigned int	is_virtfn:1;
> >  	unsigned int	reset_fn:1;
> >  	unsigned int    is_hotplug_bridge:1;
> > +	unsigned int	is_thunderbolt:1; /* Thunderbolt controller */
> 
> I'm not really keen on having this in the PCI core because the core
> doesn't need this or even know what it means.
> 
> pci_find_next_ext_capability() is available to drivers, and if
> Thunderbolt-connectedness is useful information to apple-gmux or GPU
> drivers, it's fine with me if you want to use it there.  I just don't
> see the benefit to having it in the core.

The above contradicts your statement 3 days earlier:

	"Assuming we need it, having it in struct pci_dev is fine.
	 There's no point in looking up the VSEC capability more than once."
	(http://www.spinics.net/lists/linux-pci/msg58532.html)

Please explain.

Thanks,

Lukas