From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [RFC PATCH] Documentation: devicetree: add description for generic bus properties Date: Fri, 29 Nov 2013 18:01:10 +0000 Message-ID: <20131129180110.GJ31000@mudshark.cambridge.arm.com> References: <20131127172806.GC2291@e103592.cambridge.arm.com> <20131127230650.GA6162@kroah.com> <20131128102845.GB21354@mudshark.cambridge.arm.com> <20131128173339.GB4634@e103592.cambridge.arm.com> <20131128191331.GB2385@kroah.com> <20131128193917.GC4634@e103592.cambridge.arm.com> <20131128212528.GA6144@kroah.com> <20131129114453.GC21336@mudshark.cambridge.arm.com> <20131129173701.GA5635@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20131129173701.GA5635@kroah.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Greg KH Cc: Mark Rutland , "devicetree@vger.kernel.org" , Stephen Warren , Thierry Reding , "grant.likely@linaro.org" , Dave P Martin , "linux-arm-kernel@lists.infradead.org" , Hiroshi Doyu List-Id: devicetree@vger.kernel.org On Fri, Nov 29, 2013 at 05:37:01PM +0000, Greg KH wrote: > On Fri, Nov 29, 2013 at 11:44:53AM +0000, Will Deacon wrote: > > On Thu, Nov 28, 2013 at 09:25:28PM +0000, Greg KH wrote: > > > On Thu, Nov 28, 2013 at 07:39:17PM +0000, Dave Martin wrote: > > > > On Thu, Nov 28, 2013 at 11:13:31AM -0800, Greg KH wrote: > > > > > Yes it is, you all are the ones tasked with implementing the crazy crap > > > > > the hardware people have created, best of luck with that :) > > > > > > > > Agreed. The first assumption should be that we can fit in with the > > > > existing device model -- we should only reconsider if we find that > > > > to be impossible. > > > > > > Let me know if you think it is somehow impossible, but you all should > > > really push back on the insane hardware designers that are forcing you > > > all to do this work. I find it "interesting" how this all becomes your > > > workload for their crazy ideas. > > > > Oh, I don't think we're claiming anything is impossible here :) It's more > > that we will probably want to make some changes to the device model to allow, > > for example, a device to be associated with multiple buses of potentially > > different types. > > Why would you want that? What good would that help with? It would help with devices which have their slave interface on one bus, but master to another. We need a way to configure the master side of things (IOMMU, coherency, MSI routing, etc) on one bus and configure the slave side (device probing, power management, clocks, etc) on another. > > Step one is to get the DT binding sorted, then we can try and get Linux to > > make use of it. This goes hand-in-hand with the IOMMU discussion going on > > here: > > > > http://lists.infradead.org/pipermail/linux-arm-kernel/2013-November/210401.html > > > > which is one of the issues that is hitting us right now. > > Interesting how people seem to not know how to cc: the needed > maintainers when they touch core code :( To be fair, I don't think that code was intended to be merged, and ended up sparking a discussion about what we need in the DT to represent these topologies. DT people were on CC iirc. Will