[linux-sunxi] Re: [PATCH v7 4/8] drm/sunxi: Add DT bindings documentation of Allwinner HDMI

[Jean-Francois Moine]

On Thu, 01 Dec 2016 12:41:20 +0200
Laurent Pinchart <laurent.pinchart at ideasonboard.com> wrote:

> > > If a DVI connector instead of a HDMI connector is soldered, how
> > > should such a device tree be written?
> > 
> > Use a dvi-connector instead :)
> 
> The HDMI encoder DT node doesn't (and certainly shouldn't) report what type of 
> connector is mounted on the board. Having a connector node in DT makes the 
> connector type available to the system, allowing the DRM driver to expose the 
> right connector type to userspace (it would be confusing for the user to 
> report DRM_MODE_CONNECTOR_HDMIA for a DVI connector).

The connector type, HDMI or DVI, is known by the EDID.
The user is not interested by the software indication of the connector
type: (s)he knows it because (s)he connected him/herself the display
device.
And the DRM driver does not do anything from the knowledge of the
connector type in the DT. Only the EDID may tell if the display device
may do audio streaming (direct HDMI with audio capability) or not
(direct HDMI without audio, HDMI to DVI cable, DVI physical connector).

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