On Wed, Mar 30, 2022 at 11:48:01PM +0800, Jiaxin Yu wrote: > On Wed, 2022-03-30 at 15:24 +0100, Mark Brown wrote: > > On Wed, Mar 30, 2022 at 10:06:24PM +0800, Jiaxin Yu wrote: > > > On Wed, 2022-03-30 at 13:30 +0100, Mark Brown wrote: > > > > Making a previously optional property required means that systems > > > > that > > > > previously worked may stop working unless they update their DT, > > > > DTs > > > > may > > > > be distributed separately to the kernel and perhaps even baked > > > > into > > > > firmware or similar. > > > Thank you for your detailed answer. I should keep the driver's > > > behavior > > > consistent with the description of dt-bindings. The "mediatek,hdmi- > > > codec" needs to be set as the required property. Is my > > > understanding > > > right? > > > > The binding document and code should match so if one is changed the > > other needs to be changed too. > > > > In theory we should never change a previously optional property to > > required which would mean that the code should be updated to reflect > > the > > binding document, however sometimes the DT isn't actually used as a > > stable intereface by anything for a given property or device type so > > we > > can get away with changing things. > > "however sometimes the DT isn't actually used as a stable intereface by > anything for a given property or device type so we can get away with > changing things." > > Sorry, I don't understand the real idea of this description. Does it > mean that dt-bindings in this series don't need to be updated, but the > driver? He means that usually the DT (and dt-binding) shouldn't be changed to avoid incompatibilities, but sometimes it's OK to change them. For example if there are no users of the DT yet. But in any case, like I mentioned in my latest reply [1], I don't think changing the dt-binding is the proper solution in this case. The driver should be changed instead. Thanks, Nícolas [1] https://lore.kernel.org/all/20220330152026.6nuigsldx46lue44@notapiano
