From mboxrd@z Thu Jan 1 00:00:00 1970 From: Emil Medve Subject: Re: [PATCH 3/4] dt/bindings: Introduce the FSL QorIQ DPAA QMan Date: Fri, 24 Oct 2014 04:53:52 -0500 Message-ID: <544A21B0.9040204@Freescale.com> References: <1413986972-621-1-git-send-email-Emilian.Medve@Freescale.com> <1413986972-621-3-git-send-email-Emilian.Medve@Freescale.com> <20141022143732.GB4010@leverpostej> <54480DF8.3070604@Freescale.com> <20141023112628.GC13690@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141023112628.GC13690@leverpostej> Sender: linux-doc-owner@vger.kernel.org To: Mark Rutland Cc: "scottwood@freescale.com" , "galak@kernel.crashing.org" , "corbet@lwn.net" , "robh+dt@kernel.org" , "ijc+devicetree@hellion.org.uk" , "galak@codeaurora.org" , Pawel Moll , "Geoff.Thorpe@freescale.com" , "linuxppc-dev@ozlabs.org" , "devicetree@vger.kernel.org" , "linux-doc@vger.kernel.org" List-Id: devicetree@vger.kernel.org Hello Mark, On 10/23/2014 06:26 AM, Mark Rutland wrote: >>>> +- clocks >>>> + Usage: See clock-bindings.txt and qoriq-clock.txt >>>> + Value type: >>>> + Definition: Half of the platform clock >>>> + >>> >>> I don't understand the description here. What is the clock from the PoV >>> of the QMan? Which input line on the QMan is this clock attached to? >>> >>> Is there only one clock input? Or jsut one that you need to manage at >>> the moment? >> >> As part of the programming model (QoS features specifically) QMan needs >> to know its clock speed. Prior to the existence of the >> clock-bindings.txt, a "static" clock-frequency property was/is used >> convey such information. Using clock-binding.txt to describe the >> clocking hierarchy in the SoC makes it easier with DFS, power >> management, etc. > > Ok. My concern is the phrase "Half of the platform clock" is meaingless. > The property contains a phandle + clock-specifier pair that describe a > single input clock by reference (some bindings just say "clock > reference" for that, which is fine). This is not "half" of any > particular clock. > > The description of the clock should describe what it logically is from > the PoV of the consumer (i.e. _this_ device) rather than the provider. > To me "platform clock" sounds like a description of the provider. Is > there a name for the clock input line on this device? > > Is there only a single clock input? Or just one that you care about at > the moment? This is the reference clock for QMan and is the only input clock. It's derived form the platform PLL/clock and its frequency/speed is half of the platform PLL. I'll update its description Cheers,