From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: Re: [PATCH 1/4] PCI / ACPI: Identify external PCI devices Date: Thu, 15 Nov 2018 14:16:27 +0200 Message-ID: <20181115121627.GA2500@lahna.fi.intel.com> References: <20181112160628.86620-1-mika.westerberg@linux.intel.com> <20181112160628.86620-2-mika.westerberg@linux.intel.com> <20181112180203.lx72gjfplb6xlur7@wunner.de> <20181113105636.GB11202@e107981-ln.cambridge.arm.com> <20181113112700.GT2500@lahna.fi.intel.com> <20181113114527.GA12821@e107981-ln.cambridge.arm.com> <20181115102239.GU2500@lahna.fi.intel.com> <20181115111356.GA599@e107981-ln.cambridge.arm.com> <20181115113737.GW2500@lahna.fi.intel.com> <20181115120736.pscly6zwd3k2tvd2@wunner.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181115120736.pscly6zwd3k2tvd2@wunner.de> Sender: linux-kernel-owner@vger.kernel.org To: Lukas Wunner Cc: Lorenzo Pieralisi , iommu@lists.linux-foundation.org, Joerg Roedel , David Woodhouse , Lu Baolu , Ashok Raj , Bjorn Helgaas , "Rafael J. Wysocki" , Jacob jun Pan , Andreas Noever , Michael Jamet , Yehezkel Bernat , Christian Kellner , Mario.Limonciello@dell.com, Anthony Wong , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-acpi@vger.kernel.org On Thu, Nov 15, 2018 at 01:07:36PM +0100, Lukas Wunner wrote: > On Thu, Nov 15, 2018 at 01:37:37PM +0200, Mika Westerberg wrote: > > On Thu, Nov 15, 2018 at 11:13:56AM +0000, Lorenzo Pieralisi wrote: > > > I have strong objections to the way these bindings have been forced upon > > > everybody; if that's the way *generic* ACPI bindings are specified I > > > wonder why there still exists an ACPI specification and related working > > > group. > > > > > > I personally (but that's Bjorn and Rafael choice) think that this is > > > not a change that belongs in PCI core, ACPI bindings are ill-defined > > > and device tree bindings are non-existing. > > > > Any idea where should I put it then? These systems are already out there > > and we need to support them one way or another. > > I suppose those are all Thunderbolt, so could be handled by the > existing ->is_thunderbolt bit? > > It was said in this thread that ->is_external is more generic in > that it could also be used on PCIe slots, however that use case > doesn't appear to lend itself to the "plug in while laptop owner > is getting coffee" attack. To access PCIe slots on a server you > normally need access to a data center. On a desktop, you usually > have to open the case, by which time the coffee may already have > been fetched. So frankly the binding seems a bit over-engineered > to me and yet another thing that BIOS writers may get wrong. I would not say it should include PCIe slots but there are other cables that carry PCIe and I was thinking we could make it to support those as well. I have no problem using is_thunderbolt here, though if we don't want to support non-Thunderbolt external devices this way. However, the question here is more that where I should put the _DSD parsing code if it is not suitable to be placed inside PCI/ACPI core as I've done in this patch? ;-)