From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Likely Subject: Re: clock bindings Date: Mon, 4 Apr 2011 22:50:53 -0600 Message-ID: <20110405045053.GB28817@ponder.secretlab.ca> References: <4D498AAC.3090009@gmail.com> <20110331224547.GH437@ponder.secretlab.ca> <20110401064303.GH25866@S2100-06.ap.freescale.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20110401064303.GH25866-+NayF8gZjK2ctlrPMvKcciBecyulp+rMXqFh9Ls21Oc@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Shawn Guo Cc: devicetree-discuss List-Id: devicetree@vger.kernel.org On Fri, Apr 01, 2011 at 02:43:04PM +0800, Shawn Guo wrote: > On Thu, Mar 31, 2011 at 04:45:47PM -0600, Grant Likely wrote: > > On Wed, Feb 02, 2011 at 10:47:40AM -0600, Rob Herring wrote: > > > I've started looking at the DT clock bindings in more depth. To what > > > level should the clock tree be defined in the DT? Should it be a > > > one-to-one correlation of current struct clk nodes to node in DT > > > where each node is a single input and output? Or only define a > > > single (or few) node with the inputs (oscillators) and many outputs > > > for SOC's clock controller (i.e. MX51 CCM). > > > > > > If the DT itself does not have a hierarchical construction of nodes > > > that matches the clock tree hierarchy, then creating the hierarchy > > > at run-time will be a challenge and not be very efficient. It would > > > require 1 pass for each clock node type to create all the nodes, and > > > then another pass to setup the hierarchy. > > > > Wow, it takes me a long time to reply sometimes. > > > > I'm not sure at the moment. A month ago I would have said > > "everything", but I've thought about it a lot more and I think it is > > more important that dt and non-dt users share the same code base for > > setting up internal-to-the-soc clocks. Anything available externally > > will need a node describing it in the dt, which means the support code > > shifts from registering all the clocks to matching up dt nodes to > > existing clocks where possible. > > > > For the time being, I've pushed back on registering all devices from > > the device tree for the same reason which has given some breathing > > room on the topic. It will be a topic for discussion at UDS. > > > You must have seen the hot discussion on arch/arm platform device > mess. People have so much expectation from device tree to partly > clean them up. You are going on a way which may let those people > down, at lease for quite some time :) Actually, I'm not too worried about this. The real problem is the board files, not the SoC support code, so even with changing focus a bit it will still have a huge impact on how the board files look. g.