From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sascha Hauer Subject: Re: ARM topic: Is DT on ARM the solution, or is there something better? Date: Thu, 24 Oct 2013 11:21:47 +0200 Message-ID: <20131024092147.GX30088@pengutronix.de> References: <52644A9E.3060007@wwwdotorg.org> <20131020231134.GR25034@n2100.arm.linux.org.uk> <20131021083242.GB30088@pengutronix.de> <20131021084854.GV25034@n2100.arm.linux.org.uk> <20131021092730.GF30088@pengutronix.de> <20131024072811.GS30088@pengutronix.de> <20131024090054.GA11296@ulmo.nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20131024090054.GA11296-AwZRO8vwLAwmlAP/+Wk3EA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: Rob Clark , Russell King - ARM Linux , Stephen Warren , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "ksummit-2013-discuss-cunTk1MwBs98uUxBSJOaYoYkZiVZrdSR2LY78lusg7I@public.gmane.org" List-Id: devicetree@vger.kernel.org On Thu, Oct 24, 2013 at 11:00:56AM +0200, Thierry Reding wrote: > On Thu, Oct 24, 2013 at 09:28:11AM +0200, Sascha Hauer wrote: > > On Wed, Oct 23, 2013 at 09:14:17PM -0400, Rob Clark wrote: > > > On Mon, Oct 21, 2013 at 5:27 AM, Sascha Hauer wrote: > > > >> If a subsystem doesn't work well with DT, then the choices are either: > > > >> > > > >> (a) don't use DT with the subsystem > > > > > > > > The underlying problem has nothing to do with DT. Multi component > > > > hardware does exist and won't vanish when we stop using DT. > > > > > > > >> (b) fix the subsystem > > > > > > > > I'd love to do that. Step one to this seems to be to increase the > > > > awareness that there's something wrong with DRM. > > > > > > > > > Note that I suspect your idea of "fixing drm" is going to break some > > > userspace assumptions about the hw (ie. userspace isn't expecting > > > crtcs/encoders/connectors to suddenly appear/disappear. And the funny > > > thing is, on all of this hw, that isn't going to happen anyways. > > > > I was talking about all SoC DRM drivers implementing variants of the > > same glue between drm and the multidevice nature of the components. > > > > To make that sure: I never had the intention to implement hotplug for > > drm. Also what the imx-drm driver does is not for hotplug, but only for > > binding different components together. > > I think we should be able to solve that problem generically. Essentially > we need some sort of composite device that subdevices can register with. > The composite device can keep track of what devices are needed (this > works well by walking the device tree, looking for nodes that match by > compatible and see if their status property is set to"okay") and once > all of those have been registered do whatever the specific subsystem > requires. It would be great to have a generic approach to this since subsystems like ASoC and v4l2 have the same problem. 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 | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html