From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lucas Stach Subject: Re: [PATCH] PCI: add missing DT binding for linux,pci-domain property Date: Thu, 06 Nov 2014 16:08:57 +0100 Message-ID: <1415286537.671.3.camel@pengutronix.de> References: <1415101660-26450-1-git-send-email-l.stach@pengutronix.de> <20141104120052.GE11102@e106497-lin.cambridge.arm.com> <2606632.6m38glseTk@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2606632.6m38glseTk@wuerfel> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Arnd Bergmann Cc: Liviu Dudau , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Bjorn Helgaas , "linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: devicetree@vger.kernel.org Am Dienstag, den 04.11.2014, 13:07 +0100 schrieb Arnd Bergmann: > On Tuesday 04 November 2014 12:00:52 Liviu Dudau wrote: > > > > 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) unique > > 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 number to a host > > bridge you have to ensure that all the host bridge drivers present in the system > > follow the same policy. Otherwise, potentially conflicting domain numbers > > may be assigned to root busses behind different host bridges. > > But with the latest change to the domain handling, all drivers would implement > this. I would just mention that Linux kernels older than 3.19 are probably > going to ignore this property. > Hm, I don't think we should stick those things into the binding docs, as those should not be Linux specific. IMHO the time when the parsing of a property gets implemented is a implementation detail that has nothing to do with the binding. Besides vendors always screw with this timeframes by doing backports. Regards, Lucas -- Pengutronix e.K. | Lucas Stach | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html