From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philipp Zabel Date: Fri, 07 Mar 2014 14:17:39 +0000 Subject: Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector Message-Id: <1394201859.16309.14.camel@paszta.hi.pengutronix.de> List-Id: References: <1393590016-9361-1-git-send-email-tomi.valkeinen@ti.com> <1393590016-9361-4-git-send-email-tomi.valkeinen@ti.com> <20140228155937.GQ21483@n2100.arm.linux.org.uk> <5310B567.7040605@ti.com> <20140228162327.GT21483@n2100.arm.linux.org.uk> <5316E31F.9050308@ti.com> <53183730.5060205@ti.com> In-Reply-To: <53183730.5060205@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tomi Valkeinen Cc: "devicetree@vger.kernel.org" , Linux Fbdev development list , Russell King - ARM Linux , DRI Development , Andrzej Hajda , Geert Uytterhoeven , Laurent Pinchart , "linux-arm-kernel@lists.infradead.org" , Sebastian Hesselbarth Hi, Am Donnerstag, den 06.03.2014, 10:52 +0200 schrieb Tomi Valkeinen: > On 06/03/14 10:39, Geert Uytterhoeven wrote: > > On Wed, Mar 5, 2014 at 9:41 AM, Tomi Valkeinen wrote: > >> On 28/02/14 18:23, Russell King - ARM Linux wrote: > >> > >>> That's rather a lot of compatible strings. Another possibility is: > >>> > >>> compatible = "dvi-connector"; > >>> analog; > >>> digital; > >>> single-link; > >>> dual-link; > >> > >> I made the following changes compared to the posted version. I decided > >> to leave the "single-link" out, as it's implied if "digital" is set. > >> > >> Tomi > >> > >> @@ -6,11 +6,16 @@ Required properties: > >> > >> Optional properties: > >> - label: a symbolic name for the connector > >> -- i2c-bus: phandle to the i2c bus that is connected to DVI DDC > >> +- ddc-i2c-bus: phandle to the i2c bus that is connected to DVI DDC > >> +- analog: the connector has DVI analog pins > >> +- digital: the connector has DVI digital pins > >> +- dual-link: the connector has pins for DVI dual-link > >> > >> Required nodes: > >> - Video port for DVI input > >> > >> +Note: One (or both) of 'analog' or 'digital' must be set. > > > > So dual-link needs both "digital" and "dual-link"? > > Yes. It is extra, but it felt clearer to me to have 'digital' as a > matching property for 'analog'. > > Alternatively we could have three options: > > analog; > digital-single-link; > digital-dual-link; > > My reasoning to the format I chose was basically that when a connector > supports 'digital', it contains TMDS clock and TMDS data for link 1. > Adding dual link to that adds only TMDS data for link 2, so the second > data link is kind of an additional feature, marked with a flag. > > Not a very big argument, and I'm fine with other format suggestions. I'd prefer the analog / digital / dual-link variant for aesthetic reasons. But looking at other connector types, I wonder if this should be generalized even more: For HDMI/DVI (digital) single-link means one clock pair and 3 TMDS data pairs, dual-link means one clock pair and 6 data pairs. On LVDS connectors, there usually are one clock pair and three (18-bit) or four (24-bit) LVDS data pairs, in dual channel configuration two clock pairs and 6 or 8 data pairs are used. For DisplayPort there is no separate clock pair, but 1 to 4 data pairs, and MIPI DSI again has one clock pair and a one or more data pairs. There are already optional endpoint configuration properties 'data-lanes' and 'clock-lanes' for MIPI CSI-2 defined in Documentation/devicetree/bindings/media/video-interfaces.txt. Could/should this be aligned with the same? regards Philipp