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

Sakari Ailus
2017-08-17T06:20:40Z

Sebastian Reichel wrote:
> Hi,
>
> On Thu, Aug 17, 2017 at 12:23:44AM +0300, Sakari Ailus wrote:
>> On Wed, Aug 16, 2017 at 10:59:15PM +0200, Pavel Machek wrote:
>>>> On Wed, Aug 16, 2017 at 12:03:49AM +0200, Pavel Machek wrote:
>>>>> diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt
>>>>> index 852041a..aade681 100644
>>>>> --- a/Documentation/devicetree/bindings/media/video-interfaces.txt
>>>>> +++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
>>>>> @@ -119,6 +119,8 @@ Optional endpoint properties
>>>>> as 0 (normal). This property is valid for serial busses only.
>>>>> - strobe: Whether the clock signal is used as clock (0) or strobe (1). Used
>>>>> with CCP2, for instance.
>>>>> +- clock-inv: polarity of clock/strobe signal. 0 - not inverted, 1 - inverted
>>>>> +- crc: crc is in use
>>>>
>>>> booleans in DT are not done with <0> and <1>, but as properties without
>>>> values. True = property exists, False = property does not exist.
>>
>> Now that you mention it, I remember that now.
>>
>>> 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.

Pavel: could you also add linux-media as well for the next version, please?

--
Sakari Ailus
sakari.ailus@iki.fi