From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: Re: [PATCH v7 4/8] drm/sunxi: Add DT bindings documentation of Allwinner HDMI Date: Thu, 01 Dec 2016 13:44:31 +0200 Message-ID: <3596263.47eZbXLy2S@avalon> References: <5021537.YAZCMeDTSh@avalon> <20161201123009.d2b4d9d389070200c54138ee@free.fr> Reply-To: laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org In-Reply-To: <20161201123009.d2b4d9d389070200c54138ee-GANU6spQydw@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Jean-Francois Moine Cc: Maxime Ripard , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "moinejf-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org" , "linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org" , Rob Herring , Icenowy Zheng , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org On Thursday 01 Dec 2016 12:30:09 Jean-Francois Moine wrote: > On Thu, 01 Dec 2016 12:41:20 +0200 Laurent Pinchart 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. That's not correct. The connector type reported by DRM to userspace can be used as a hint to information the user about connectors. Displaying a "Please connect a monitor to the HDMI connector" is confusing when the system has a DVI connector. > 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). -- Regards, Laurent Pinchart