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