On 2/1/08, Kumar Gala <[EMAIL PROTECTED]> wrote: > > > --- a/Documentation/powerpc/booting-without-of.txt > > +++ b/Documentation/powerpc/booting-without-of.txt > > @@ -1675,7 +1675,6 @@ platforms are moved over to use the flattened- > > device-tree model. > > [EMAIL PROTECTED] { > > device_type = "network"; > > compatible = "ucc_geth"; > > - model = "UCC"; > > device-id = <1>; > > can we change device-id to cell-index?
<aside> Here's a thought; do we really need a cell-index at all? (and I'm talking in general; not just this specific case). I'm starting to think we should migrate away from using it. cell-index has been useful for things like clock controllers to know what offset into a shared clock control register or something like that and a driver would pass the cell-index value to the shared reg driver when requesting service. However, I think the information encoded in cell-index is already encoded in the device tree in a different manor. Typically, shared registers and the like are all chip specific and the behaviour of the shared register drivers usually needs to be tweaked for different SoCs. Each ip core on an SoC is already uniquely indexed via the reg property. True, 'reg' is sparse (0x2000, 0x2200, 0x2300, ...) whereas cell-index is tight (0,1,2,3,...), but I don't think that introduces any additional difficulty. So, instead of a driver passing it's cell-index value to the shared reg driver, it would pass it's reg base instead. The shared register driver could then choose an internal representation that makes sense for it instead of whatever layout was chosen by the device tree. Dropping cell-index would mean one less property to keep in sync when tailoring device trees. (== less complexity for board porters). Besides, the purpose of cell-index is often misunderstood already by people trying to use it to describe port numbers (ttyS0, ttyS1, etc). Thoughts? </aside> Cheers, g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev