From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Grandegger Subject: Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking Date: Wed, 01 Apr 2009 09:40:13 +0200 Message-ID: <49D31A5D.8030204@grandegger.com> References: <20090331124338.531903515@denx.de> <20090331124348.330571158@denx.de> <20090331230626.GB23304@yookeroo.seuss> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090331230626.GB23304-787xzQ0H9iRg7VrjXcPTGA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-mnsaURCQ41sdnm+yROfE0A@public.gmane.org Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-mnsaURCQ41sdnm+yROfE0A@public.gmane.org To: Wolfgang Grandegger , linuxppc-dev-mnsaURCQ41sdnm+yROfE0A@public.gmane.org, devicetree-discuss-mnsaURCQ41sdnm+yROfE0A@public.gmane.org List-Id: devicetree@vger.kernel.org David Gibson wrote: > On Tue, Mar 31, 2009 at 02:43:39PM +0200, Wolfgang Grandegger wrote: >> The I2c node property "fsl,preserve-clocking" allows to overtake the >> clock settings from the boot loader and avoids the hard-coded setting. > > Hrm. This is dubious. The device tree should generally describe > hardware, not OS/driver behaviour which is what this appears to be > doing. There are exceptions, but you need to justify them. I think the purpose of this property is clear. How would you provide that functionality instead? I suggested that a "clock-frequency = <0>" property should do the trick but Grant preferred to be more explicit. Wolfgang. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <49D31A5D.8030204@grandegger.com> Date: Wed, 01 Apr 2009 09:40:13 +0200 From: Wolfgang Grandegger MIME-Version: 1.0 To: Wolfgang Grandegger , linuxppc-dev@ozlabs.org, devicetree-discuss@ozlabs.org Subject: Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking References: <20090331124338.531903515@denx.de> <20090331124348.330571158@denx.de> <20090331230626.GB23304@yookeroo.seuss> In-Reply-To: <20090331230626.GB23304@yookeroo.seuss> Content-Type: text/plain; charset=ISO-8859-1 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , David Gibson wrote: > On Tue, Mar 31, 2009 at 02:43:39PM +0200, Wolfgang Grandegger wrote: >> The I2c node property "fsl,preserve-clocking" allows to overtake the >> clock settings from the boot loader and avoids the hard-coded setting. > > Hrm. This is dubious. The device tree should generally describe > hardware, not OS/driver behaviour which is what this appears to be > doing. There are exceptions, but you need to justify them. I think the purpose of this property is clear. How would you provide that functionality instead? I suggested that a "clock-frequency = <0>" property should do the trick but Grant preferred to be more explicit. Wolfgang.