Re: [PATCH v3 1/2] dt-bindings: drm/bridge: adv7511: Add regulator bindings

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Mark,

On Tuesday 29 Nov 2016 11:01:25 Mark Brown wrote:
> 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.

Sounds good to me, thanks.

> 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.

I try to add a (CC'ing xxx) at the beginning of the e-mail to draw attention 
when a question is targetted at a particular person. If that's not enough I 
can change the subject, but might forget to do so from time to time. Or you 
could whitelist me, unless I'm already blacklisted ;-)

-- 
Regards,

Laurent Pinchart

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