From mboxrd@z Thu Jan 1 00:00:00 1970 From: Liviu Dudau Subject: Re: [PATCH] PCI: add missing DT binding for linux,pci-domain property Date: Tue, 4 Nov 2014 12:00:52 +0000 Message-ID: <20141104120052.GE11102@e106497-lin.cambridge.arm.com> References: <1415101660-26450-1-git-send-email-l.stach@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1415101660-26450-1-git-send-email-l.stach@pengutronix.de> Content-Disposition: inline Sender: linux-pci-owner@vger.kernel.org To: Lucas Stach Cc: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , "devicetree@vger.kernel.org" , Bjorn Helgaas , "linux-pci@vger.kernel.org" List-Id: devicetree@vger.kernel.org On Tue, Nov 04, 2014 at 11:47:40AM +0000, Lucas Stach wrote: > This property was added by 41e5c0f81d3e > (of/pci: Add pci_get_new_domain_nr() and of_get_pci_domain_nr()) > without the required binding documentation. As this property > will be supported by a number of host bridge drivers going forward, > add it to the common PCI binding doc. >=20 > Signed-off-by: Lucas Stach > --- > This is a non-critical fix, but may still qualify for 3.18-rc as > the property was added in this release cycle. Hi Lucas, Thanks for taking care of this, sorry it slipped through the cracks of last minute changes in this area. > --- > Documentation/devicetree/bindings/pci/pci.txt | 10 ++++++++++ > 1 file changed, 10 insertions(+) >=20 > diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Document= ation/devicetree/bindings/pci/pci.txt > index 41aeed38926d..b754f786ed5e 100644 > --- a/Documentation/devicetree/bindings/pci/pci.txt > +++ b/Documentation/devicetree/bindings/pci/pci.txt > @@ -7,3 +7,13 @@ And for the interrupt mapping part: > =20 > Open Firmware Recommended Practice: Interrupt Mapping > http://www.openfirmware.org/1275/practice/imap/imap0_9d.pdf > + > +Additionally to the properties specified in the above standards a ho= st bridge > +driver implementation may support the following properties: > + > +- linux,pci-domain: > + If present this property assigns a fixed PCI domain number to a h= ost bridge, > + otherwise an unstable (across boots) unique number will be assign= ed. > + It is recommended to either not set this property at all or set i= t for all > + host bridges in the system, otherwise potentially conflicting dom= ain numbers > + may be assigned to root buses behind different host bridges. > --=20 > 2.1.1 >=20 While the description is potentially correct, what it fails to explain = is that the choice of using the property or generating an unstable (across boots) u= nique number is actually the choice of the host bridge driver at the moment. = I know that my earlier implementations were defaulting to the automatic numbering, = but that has been dropped from the final series as Rob Herring was objecting to it. There is still scope to adopt a wide policy here, but for now it should= say something to the tune: If present this property assigns a fixed PCI domain number to a host= bridge, otherwise an unstable (across boots) unique number will be assigned. If you decide to use the property to assign a fixed PCI domain numbe= r to a host bridge you have to ensure that all the host bridge drivers present i= n the system follow the same policy. Otherwise, potentially conflicting domain nu= mbers may be assigned to root busses behind different host bridges. Best regards, Liviu --=20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- =C2=AF\_(=E3=83=84)_/=C2=AF