On Tue, Nov 29, 2016 at 11:11:03AM +0200, Laurent Pinchart wrote: > On Tuesday 29 Nov 2016 13:41:33 Archit Taneja wrote: > > I thought we couldn't add mandatory properties once the device is already > > present in DT for one or more platforms. > You can, as long as you treat them as optional in the driver to retain > backward compatibility. The DT bindings should document the properties > expected from a new platform (older versions of the bindings will always be > available in the git history). The device probably never worked without power... note that the kernel will substitute in dummy regulators for anything that isn't explicitly mapped so it won't actually break anything. > > Say, if we do make it mandatory for future additions, we would need to have > > DT property for the supplies for the new platforms. If the regulators on > > these boards are fixed supplies, they would be need to be modeled > > using "regulator-fixed", possibly without any input supply. Is that > > what you're suggesting? > That's the idea, yes. Clock maintainers have a similar opinion regarding the > clock bindings, where a clock that is not optional at the hardware level > should be specified in DT even if it's always present. > Mark, any opinion ? It's best practice to always describe the power. The kernel will cope if people don't but it's not unknown for drivers to discover a reason for wanting information about their power and hard to retrofit that if it's not been in there from the get go. Please note that if you're going to CC me into a graphics thread there's a good chance I will miss it, I get copied on quite a lot of graphics related mail that's not really relevant so I often skip it. Changing the subject line would help with that.
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