On Tue, Mar 19, 2013 at 07:07:34AM +0000, David Gibson wrote: > On Mon, Mar 18, 2013 at 09:48:16AM +0000, Lorenzo Pieralisi wrote: > > On Mon, Mar 18, 2013 at 03:09:28AM +0000, David Gibson wrote: > > > On Mon, Mar 11, 2013 at 05:06:57PM +0000, Lorenzo Pieralisi wrote: > > > > Hi David, > > > > > > > > thanks for your feedback. > > > > > > > > On Wed, Mar 06, 2013 at 09:57:14PM +0000, David Gibson wrote: > > > > > On Fri, Feb 15, 2013 at 05:21:02PM +0000, Lorenzo Pieralisi wrote: > > > [snip] > > > > > > Each foo@2000000 reg property maps to a device that represents a > > > > > > bus master > > > > > > (to make it clearer, a foo@2000000 reg property defines an address > > > > > > space that > > > > > > belongs to a bus master, ie the address space represents a > > > > > > programming > > > > > > interface specific to that master; in the bindings above address > > > > > > 0x2000000 is > > > > > > the address at which acme1 device can programme its "foo" > > > > > > interface, address > > > > > > 0x2001000 is the address at which acme2 device can programme its > > > > > > "foo" > > > > > > interface). > > > > > > > > > > Ok. I think annotating the existing reg property like this is a very > > > > > bad idea. I haven't seen all the previous discussion, so I'm not > > > > > totally clean on what this affinity concept is about. But as I > > > > > understand it, these "slave" resources cannot be treated like an > > > > > ordinary resource in in the reg property. That means an older client > > > > > will potentially misinterpret "reg" because it doesn't know about > > > > > "affinity". > > > > > > > > Not really, "reg" still complies with the current DT bindings. Affinity > > > > is there to associate a reg property to a "master" but the reg property > > > > definition does not change. I do not think backward compatibility is a > > > > problem per-se here. > > > > > > Ok, I did not understand the problem properly. > > > > > > > > Worse, again, if I've understood correctly, resources with different > > > > > "masters" are essentially in different logical address spaces. "reg" > > > > > properties should always sit in the logical address space representing > > > > > the parent node's bus. Different address spaces could also have > > > > > different address sizes, which would really complicate parsing "reg". > > > > > > > > I think we need to post what we have, it is really complex to explain > > > > the issue without a concrete example. To cut a long story short I > > > > would not say that the resources sit in different address spaces, it is > > > > that we need to associate those address ranges with specific bus > > > > masters. > > > > > > > > We have to have a way to say: > > > > > > > > "Address range 0x80001000 - 0x80001fff is used to programme the control > > > > registers associated with the port connected to master X". > > > > > > > > When a CPU wants to programme a control port for a specific master, it > > > > needs to know what address range should be programmed. > > > > > > > > I mentioned "resources" instead of addresses since the problem we are > > > > having is the same when it comes to map IRQs to set of CPUS. We need > > > > to associate a resource (IRQ or address) to a set of cpus (or more in > > > > general, masters). > > > > > > Hrm. See, I think I may be misunderstanding the problem again, > > > because with this description I can see no problem. It's already up > > > to the device binding to describe the purpose of each entry in the reg > > > property. So what's the problem with it just being part of the > > > binding to say which reg entry is associated with which master port? > > > > That's exactly what we are trying to do. But to associate the reg > > property to a master port we need a phandle, how can we pull that off > > otherwise ? > > Ah, right. I was meaning that the binding specifies the abstract port > number that each reg entry is associated with. I'm fine with adding a > property to map the port numbers to master devices on the other end. > I think treating it in two steps like that is better than thinking of > the master phandles being directly associated with reg entries, > because it also handles cases like having a bank of common/global > registers not associated with any port/master, or cases where the > ports aren't all identical and some need more resources than others.
That's fine by me. Can you provide me with an example of how the bindings should tie a specific reg property to an abstract port number ? reg properties ordering (ie index) ? Or port number encoded in the reg property itself ? Thanks, Lorenzo _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
