[Intel-gfx] [PATCH v5 7/7] drm: create hdmi output property

[Sharma, Shashank]

Regards

Shashank


On 6/23/2017 2:50 PM, Daniel Vetter wrote:
> On Thu, Jun 22, 2017 at 10:33 AM, Sharma, Shashank
> <shashank.sharma at intel.com> wrote:
>>> - The property values should be limited to what the driver can support, I
>>>     guess that would mean limiting the available ycbcr modes? Or does all
>>>     our hw support all the modes, including 420 (on the sink side)?
>> This property is targeted at DRM layer, so naturally its for all the HWs
>> along with Intel HW, so it serves a big range.
>> All our HDMI 1.4 sources support RGB444, and after this series, can support
>> YCBCR444.
>> All HDMI 2.0 sources should support YCBCR420, but they can declare this
>> using a bool variable which I added in patch 3 (ycbcr420_allowed)
>> As we are targeting both HDMI 1.4 as well as HDMI 2.0 (Src and Sink), as a
>> whole we are covering all options.
> Yes, we need to define values for everything, since it's a generic
> property. But for a given driver imo we should only allow the values
> that are actually supported. An example would be the rotation
> property, which supporsts X/Y-mirror and rotation by 90° steps. But on
> a given i915 platform we only register support for the stuff the
> driver/hw can do, e.g. pre-gen9 do not register 90/270° rotation. I
> think we should do the same here. See
> drm_plane_create_rotation_property(), specifically the
> supported_rotations parameter.
Ah, I got your point now, and its valid.
If you see the I915 level handlers of YCBCR functions (added in patch 
10) they are taking care of blocking
anything which is not supported by driver for this platform, based on:
- The source capability
- The sink capability
- User preference of the property.
So on a whole, set of Intel platforms cover all the values of property, 
but at driver level we make sure to allow only what is suitable for this 
source + sink combination.
- Shashank
>
> Cheers, Daniel