On Tue, Apr 10, 2018 at 01:26:41PM +0200, Heiko Stuebner wrote: > Hi Robin, > > Am Dienstag, 10. April 2018, 13:18:48 CEST schrieb Robin Murphy: > > On 10/04/18 10:26, Heiko Stuebner wrote: > > > Rockchip IOMMUs are used without explicit clock handling for 4 years > > > now, so we should keep compatibility with old devicetrees if possible. > > > Therefore make iommu clocks optional. > > > > Do we need to touch the binding itself? Obviously the driver has to > > treat clocks as optional in existing DTs (and I feel a bit dumb now for > > managing to overlook that in review), but the binding effectively only > > covers future DTs, and I'd assume we want to encourage the clocks to be > > correctly specified there. I'd prefer the DT docs reflect what is correct for new/current dts files. That's the only way the docs can validate the dts files. > I guess that depends on your definition of the timespan for backwards > compatibility. I'm always starting out at indefinite till convinced > otherwise ;-). Hence the clocks would need to stay optional for (nearly) > forever. > > Also, having the binding claim them as required but the code handling > them as optional just calls for someone to remove the optional handling :-D A comment in the code saying why missing clocks are allowed should suffice. > Not sure if there is a established way of saying > "we want this for all future devices, but allow it to be missing for old dts". We don't really... Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
