From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Mon, 17 Oct 2011 17:02:05 +0200 Subject: [RFC] clocktree representation in the devicetree In-Reply-To: <20111017102921.GA18141@pengutronix.de> References: <20111017102921.GA18141@pengutronix.de> Message-ID: <201110171702.05319.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Monday 17 October 2011, Sascha Hauer wrote: > The following is an attempt to represent the clocktree of a i.MX53 in > the devicetree. I created this to see how it would look like and to > start a discussion whether we want to move in this direction or not. Very good, thanks for getting this started! > Some things to consider: > > - It seems to be very flexible. A board can customize the clock tree > by just adding some clk-parent= properties to the muxers. > - clocks can easily be associated with devices. > > but: > > - The following example registers 127 new platform devices and it's > not even complete. This adds significant overhead to initialization. I don't understand enough about the clock trees to understand if the dts representation is good, but it I don't see a reason to represent it as lots of platform devices in linux. We can have lots of device_nodes in the device tree that are not a platform_device but we can still access them through the of_*() functions. Ideally, we would encapsulate all the clock tree parsing in the clk subsystem and provide high-level interfaces to clkdev drivers from there. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [RFC] clocktree representation in the devicetree Date: Mon, 17 Oct 2011 17:02:05 +0200 Message-ID: <201110171702.05319.arnd@arndb.de> References: <20111017102921.GA18141@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20111017102921.GA18141@pengutronix.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Sascha Hauer Cc: devicetree-discuss@lists.ozlabs.org, Grant Likely , Richard Zhao , Shawn Guo , linux-arm-kernel@lists.infradead.org, Mike Turquette List-Id: devicetree@vger.kernel.org On Monday 17 October 2011, Sascha Hauer wrote: > The following is an attempt to represent the clocktree of a i.MX53 in > the devicetree. I created this to see how it would look like and to > start a discussion whether we want to move in this direction or not. Very good, thanks for getting this started! > Some things to consider: > > - It seems to be very flexible. A board can customize the clock tree > by just adding some clk-parent= properties to the muxers. > - clocks can easily be associated with devices. > > but: > > - The following example registers 127 new platform devices and it's > not even complete. This adds significant overhead to initialization. I don't understand enough about the clock trees to understand if the dts representation is good, but it I don't see a reason to represent it as lots of platform devices in linux. We can have lots of device_nodes in the device tree that are not a platform_device but we can still access them through the of_*() functions. Ideally, we would encapsulate all the clock tree parsing in the clk subsystem and provide high-level interfaces to clkdev drivers from there. Arnd