From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Clark Subject: Re: Best practice device tree design for display subsystems/DRM Date: Thu, 4 Jul 2013 11:11:59 -0400 Message-ID: References: <20130702204255.2044c01b@armhf> <20130702191923.GD13924@flint.arm.linux.org.uk> <51D330AC.5060903@gmail.com> <51D348F5.2080205@gmail.com> <00ae01ce77cb$524d57f0$f6e807d0$%dae@samsung.com> <20130703090242.GM516@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130703090242.GM516@pengutronix.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org Errors-To: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org To: Sascha Hauer Cc: Jean-Francois Moine , Daniel Drake , devicetree-discuss@lists.ozlabs.org, dri-devel@lists.freedesktop.org, Russell King , Sebastian Hesselbarth List-Id: devicetree@vger.kernel.org On Wed, Jul 3, 2013 at 5:02 AM, Sascha Hauer wrote: > On Wed, Jul 03, 2013 at 05:57:18PM +0900, Inki Dae wrote: >> > video { >> > /* Single video card w/ multiple lcd controllers */ >> > card0 { >> > compatible = "marvell,armada-510-display"; >> > reg = <0 0x3f000000 0x1000000>; /* video-mem hole */ >> > /* later: linux,video-memory-size = <0x1000000>; */ >> > marvell,video-devices = <&lcd0 &lcd1 &dcon>; >> > }; >> > >> > /* OR: Multiple video card w/ single lcd controllers */ >> > card0 { >> > compatible = "marvell,armada-510-display"; >> > ... >> > marvell,video-devices = <&lcd0>; >> > }; >> > >> > card1 { >> > compatible = "marvell,armada-510-display"; >> > ... >> > marvell,video-devices = <&lcd1>; >> > }; >> > }; >> >> Sorry but I'd like to say that this cannot be used commonly. Shouldn't you >> really consider Linux framebuffer or other subsystems? The above dtsi file >> is specific to DRM subsystem. And I think the dtsi file has no any >> dependency on certain subsystem so board dtsi file should be considered for >> all device drivers based on other subsystems: i.e., Linux framebuffer, DRM, >> and so no. So I *strongly* object to it. All we have to do is to keep the >> dtsi file as is, and to find other better way that can be used commonly in >> DRM. > > +1 for not encoding the projected usecase of the graphics subsystem into > the devicetree. Whether the two LCD controllers shall be used together > or separately should not affect the devicetree. devicetree is about > hardware description, not configuration. I do like the supernode idea, it would have avoided the ugly global-list-of-sub-devices in tilcdc (and probably some other drivers). As for projection of use-case, and whether it is something drm specific or not.. if there is a way to make it generic enough that it could work for fbdev, well I suppose that is nice. Not a hard requirement in my mind, or at least it is a secondary priority compared to having a better way to having drm devices composed of sub-{devices,nodes,whatever}. BR, -R > Sascha > > -- > Pengutronix e.K. | | > Industrial Linux Solutions | http://www.pengutronix.de/ | > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/dri-devel