From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [PATCH v7 10/11] ARM: at91/dt: add LCD panel description to sama5d3xdm.dtsi Date: Mon, 6 Oct 2014 15:58:18 +0200 Message-ID: <20141006155818.0bc36b3d@bbrezillon> References: <1412175188-28278-1-git-send-email-boris.brezillon@free-electrons.com> <1412175188-28278-11-git-send-email-boris.brezillon@free-electrons.com> <20141006110115.GH25202@ulmo> <20141006142538.76d2df29@bbrezillon> <20141006124014.GD26833@ulmo> <20141006151111.446ed7d6@bbrezillon> <20141006133048.GE26921@ulmo> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141006133048.GE26921@ulmo> Sender: linux-pwm-owner@vger.kernel.org To: Thierry Reding Cc: David Airlie , dri-devel@lists.freedesktop.org, Nicolas Ferre , Jean-Christophe Plagniol-Villard , Alexandre Belloni , Andrew Victor , Samuel Ortiz , Lee Jones , linux-pwm@vger.kernel.org, Rob Clark , linux-arm-kernel@lists.infradead.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Mark Yao List-Id: devicetree@vger.kernel.org On Mon, 6 Oct 2014 15:30:59 +0200 Thierry Reding wrote: > On Mon, Oct 06, 2014 at 03:11:11PM +0200, Boris Brezillon wrote: > > On Mon, 6 Oct 2014 14:40:15 +0200 > > Thierry Reding wrote: > > > > > On Mon, Oct 06, 2014 at 02:25:38PM +0200, Boris Brezillon wrote: > > > > On Mon, 6 Oct 2014 13:01:16 +0200 Thierry Reding wrote: > > > > > On Wed, Oct 01, 2014 at 04:53:07PM +0200, Boris Brezillon wrote: > > > > > [...] > > > > > > diff --git a/arch/arm/boot/dts/sama5d3xdm.dtsi b/arch/arm/boot/dts/sama5d3xdm.dtsi > > > [...] > > > > > > + backlight = <&backlight>; > > > > > > + power-supply = <&panel_reg>; > > > > > > + #address-cells = <1>; > > > > > > + #size-cells = <0>; > > > > > > + status = "disabled"; > > > > > > + > > > > > > + port@0 { > > > > > > + #address-cells = <1>; > > > > > > + #size-cells = <0>; > > > > > > + > > > > > > + panel_input: endpoint@0 { > > > > > > + reg = <0>; > > > > > > + remote-endpoint = <&hlcdc_panel_output>; > > > > > > + }; > > > > > > }; > > > > > > > > > > There's no support for OF graphs in simple-panel, so this is unused, > > > > > isn't it? > > > > > > > > Actually I use it in my atmel_hlcdc_ouput implementation to figure out > > > > the link between a panel and a device connected on the RGB/DPI bus. > > > > > > That's kind of weird and one of the reasons why I can't make myself like > > > the OF graph bindings. It requires drivers for one device to reach into > > > the device tree node of some other device and look for content. Or put > > > another way, a DT node for a panel that works on one platform doesn't > > > work on another because the display controller needs additional DT > > > content that isn't required by the original binding for the panel. > > > > I also have a working POC of a DPI bus implementation (with DPI support > > in panel-simple driver). > > > > This is a solution I developed to provide a generic DPI implementation > > in my HLCDC driver and rely on generic external implementations for > > slave devices (panels, encoders, ...). > > > > But, IIRC, Laurent was not in favor of a bus approach because the DPI > > bus is just a data bus and not a control bus. > > > > Anyway, I'll clean it up and post an RFC. > > According to the MIPI website there are also control signals and a > command set to control display behaviour. Does your implementation > handle any of that? No it doesn't, and I'm pretty sure what I call DPI does not exactly respect the MIPI DPI standard (and as such should not be called DPI, but this is another problem). This infrastructure provides a way for devices connected on a DPI bus to agree on a video_bus_format (in my case RGB888, RGB666, ...). -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com