Re: [PATCH] drm/panel: auo novatek 1080p video mode panel

[Thierry Reding <thierry.reding@gmail.com>]

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On Mon, Aug 17, 2015 at 10:48:20AM -0400, Rob Clark wrote:
> On Mon, Aug 17, 2015 at 7:38 AM, Thierry Reding
> <thierry.reding@gmail.com> wrote:
> > On Mon, Aug 10, 2015 at 12:54:20PM -0700, Bjorn Andersson wrote:
> >> On Fri 07 Aug 09:11 PDT 2015, Rob Clark wrote:
> >>
> >> > On Fri, Aug 7, 2015 at 9:19 AM, Thierry Reding <thierry.reding@gmail.com> wrote:
> >> > > On Tue, Jul 21, 2015 at 03:36:02PM -0400, Rob Clark wrote:
> >> [..]
> >> > >> +- compatible: should be "auo,novatek-1080p-vid"
> >> > >
> >> > > This looks a little generic for a compatible string. Can't we get at the
> >> > > specific panel model number that's been used? What if AUO ever produced
> >> > > some other Novatek panel with a 1080p resolution?
> >> >
> >> > Maybe Sony or someone else can chime in?  That somewhat generic name
> >> > was all I could get from downstream android kernel.  I'm sure there is
> >> > a better possible name, although I have no means to find that out
> >> > myself.
> >> >
> >>
> >> We're working on it.
> >>
> >> > > Also, what's the -vid suffix for?
> >> >
> >> > the same panel seems to also work in cmd mode.. so idea was to have
> >> > -vid and -cmd compat strings to choose which mode to operate in.
> >> >
> >>
> >> An alternative would be to make it a bool property, to indicate video
> >> mode - following how the framework is implemented.
> >
> > Please, let's not do either. This doesn't belong in the compatible
> > string. The compatible string specifies the panel, and the panel
> > supports both video and command modes. That's implied by the compatible
> > string.
> >
> > Which mode to use is a configuration or policy decision and therefore
> > doesn't belong in device tree. It should be up to the display driver to
> > determine what the preferred mode of operation is.
> 
> I would call it a "system integrator decision"..   and at least
> currently we don't have anywhere better than DT for that.  Maybe it's
> one of those "if all you have is a hammer, everything looks like a
> nail" things..

If it were a system integrator decision then I'd agree it should be
parameterizable in DT. But to my knowledge you can run any command mode
capable display in video mode just fine.

Thierry

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