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

[Daniel Vetter]

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.

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch