On Jun 12, 2011, at 9:59 AM, Russell King - ARM Linux wrote: > On Sun, Jun 12, 2011 at 11:47:59AM -0400, Nicolas Pitre wrote: >> On Sun, 12 Jun 2011, Russell King - ARM Linux wrote: >>> And we've ended up with a fucked up situation which is extremely >>> fragile, and actually makes me _NOT_ want to convert any existing >>> platforms to use DT in the least. >> >> Agreed. I don't think that anything older than OMAP2 is worth >> converting to DT. The return on the investment is simply not worth it, >> other than for experimental purposes. > > I think you haven't appreciated the situation - let's take PXA as an > example. PXA has been around for years, and IP in the latest silicon > is present in many of the older silicons too. > > There's two issues here: > > 1. If we port existing drivers over to use DT as a means to shrink the > size of the kernel, we need _all_ PXA using platforms to use DT. > > 2. If we continue having board support for PXA submitted, we want it to > use DT support. > > The result will be a mess of some bits of PXA using DT, other bits using > statically declared stuff. It may get to the point where on some PXA > platforms DT is used to describe some of the system, and on a different > PXA platform, it describes some other but needs some static stuff. > > I don't see this as a sustainable way forward. If we're going to move a > particular SoC over to DT, we need to move the entire SoC over. We can't > do this half-heartedly. > > And that means we _must_ deal with accepting ATAGs from existing boot > loaders, with that information taking precidence over the DT blob > supplied with the kernel.
The only other way out would be to have a small ATAG interpreter that modified/generated the DT so that the rest of the kernel could rely on it completely. This would fatten what is a very slim later right now, but it would mean the whole rest of the kernel could trust the DT blob as gospel. Warner _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
