From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH 10/14] PCI: tegra: Move PCIe driver to drivers/pci/host Date: Tue, 15 Jan 2013 22:14:41 +0100 Message-ID: <20130115211441.GA13139@avionic-0098.adnet.avionic-design.de> References: <1357764194-12677-1-git-send-email-thierry.reding@avionic-design.de> <20130114095706.GA23467@arm.com> <20130115120855.GA5637@avionic-0098.adnet.avionic-design.de> <201301151244.12767.arnd@arndb.de> <20130115154038.GA11241@arm.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4171163522720820654==" Return-path: In-Reply-To: <20130115154038.GA11241-5wv7dgnIgG8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Andrew Murray Cc: Jason Gunthorpe , Russell King , "linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org" , Bjorn Helgaas , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org --===============4171163522720820654== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="sdtB3X0nJg68CQEu" Content-Disposition: inline --sdtB3X0nJg68CQEu Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jan 15, 2013 at 03:40:38PM +0000, Andrew Murray wrote: > On Tue, Jan 15, 2013 at 12:44:12PM +0000, Arnd Bergmann wrote: > > On Tuesday 15 January 2013, Thierry Reding wrote: > > > I'm not sure I follow you're reasoning here. Is it possible to use MS= Is > > > without PCI? If not then I think there's little sense in keeping the > > > implementations separate. > >=20 > > Conceptually, you can use MSI for any device, but the Linux interfaces > > for MSI are tied to PCI. If you use an MSI controller for a non-PCI > > device, it would probably just appear as a regular interrupt controller. > >=20 > > > Furthermore, if MSI controller and PCI host bridge are separate entit= ies > > > how do you look up the MSI controller given a PCI device? > >=20 > > The host bridge can contain a pointer ot the MSI controller. You can > > have multiple host bridges sharing a single MSI controller or you > > can have separate ones for each host. >=20 > Yes and I hoped this relationship would be described by a device tree pha= ndle > as is done for relating devices to their interrupt-parent (where device t= rees > are used). This would provide (arguably unnecessarily) greater flexibilit= y, > e.g. if you have two PCI/MSI controller pairs, the MSIs only offer limite= d MSIs > and you only use one PCI fabric - you could service different parts of the > fabric by different MSI controllers (assuming you relate MSI controllers = to > part of the fabric and that you'd want to). Perhaps there would be benefi= ts for > virtualisation as well? Is there actually hardware that supports this? I assumed that the MSI controller would have to be tightly coupled to the PCI host bridge in order to raise an interrupt when an MSI is received via PCI. Thierry --sdtB3X0nJg68CQEu Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIcBAEBAgAGBQJQ9cbBAAoJEN0jrNd/PrOhtl4P/jFRPjJMBYsIefiaxa04+iqT 3x9QHWpfSoQabBZedImODOBW//x/WY95wzU1svRNSn9KRP57HNoI1dSetfx7dsxv UWJ5lklcJjfBCgj7m2WyG9V9Oh1YrZYJ006pie/Qi5i4YsVuLwAbXc5HyhwHHBzZ /Xm3QRPqAyXHY/mWLdqRDMMC0EntcfK6VxiM7vGyhYlFDu/0Vok7leXUXu1KB4/c yDVHB7miuzYAqX4BhrCk2Qvyt2vB7+EU40ZNOahWOJA0IYY9PcAHN36/WB6JKxFu 6my0R/Hl9XqsLim6e8nEbE6oglNnDgSITjKD+GHrQ7Jk+crhUyLBWbJpRpDVCI3Z TqKhJgaHB5nOal4aCy3rCWx9Bzg6IT+LN3xGjLtzx3OxwCbDAdDjTO9knF4FEu3h QlRMcx0Nm/vKmXE8GSeDBvjbDIoz6fAILZoIhDYG7cAcjeshDuUYLa9ZKJDxrsZU VlVI51jMty+wLcAY9yVL3TYo/pPH96Iw4xNPC7gGSFe/QELh7coynxeEOjGxcC1C BuuJrVP3iN1ozDsdU4N5sBqJMnn2yiuIHxznScPifa/9TK44OcmDffKUFOOYOXTV raEZJjmFfCQqQf7FWdQcgK7KEYLB+5rAPhJxw+kdA5D5y8t6IFBTPn1faIf9e2XE SQaQ+rKu8bPN9+wyPtr3 =JrIc -----END PGP SIGNATURE----- --sdtB3X0nJg68CQEu-- --===============4171163522720820654== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ devicetree-discuss mailing list devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org https://lists.ozlabs.org/listinfo/devicetree-discuss --===============4171163522720820654==--