Re: [PATCH] nokia n900: update dts with camera support

[Ivaylo Dimitrov]

Hi

On 28.08.2017 18:07, Sakari Ailus wrote:
> Hi Pavel,
>
> On Mon, Aug 28, 2017 at 03:59:59PM +0200, Pavel Machek wrote:
> > Hi!
> >
> > > > > Well, strobe property above already uses = <0>/<1> format, as do
> > > > > others.
> > > >
> > > > > Problem with "false = property does not exist" is that you don't know
> > > > > if it is "someone forgot to define it" or "someone made a typo" or
> > > > > "dts is too old to know about this property" or "the property indeed
> > > > > should be false"...
> > > >
> > > > As this is an established practice, I think we should follow it for bool
> > > > properties.
> > >
> > > Yes it's common practice, there is also device_property_read_bool()
> > > to get the value.
> > >
> > > > We could change the existing ones, too, and leave some extra checks in
> > > > place to handle old dtbs.
> > >
> > > The following should be downward compatible:
> > >
> > > var = read_bool();
> > > if (var && !read_int())
> > >      var = false;
> > >
> > > Btw. DT people should be CC'd for DT binding additions/changes.
> >
> > Ok, so for now we do crc=1 by default. Now we'd like to have crc
> > support configurable in the dts. But if we just introduce "crc;"
> > option, it will break old dts users. We could introduce "no-crc;" and
> > that would work in this particular case, but will break when we want
> > different defaults at different devices.
> >
> > Anyway, introducing "no-crc;" seems pretty ugly to me. I'd rather do
> > "crc=<0>;", in a similar way we handle other options now.
>
> The same issue actually exists for CSI-2: the CRC is typically enabled and
> I think you can at least disable the check (in OMAP3 ISP). Do we have a
> need to disable it at the moment for any purpose? I think I've seen this
> was disabled somewhere but it may just as well be a thoughtlessly written
> configuration.

Front camera has crc disabled in Nokia kernel. I am not sure the sensor 
supports crc at all.

Regards,
Ivo