From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH] i2c-qoriq: modified compatibility for correct prescaler Date: Tue, 25 Nov 2014 19:41:37 -0600 Message-ID: <1416966097.15957.171.camel@freescale.com> References: <1413538026-15739-1-git-send-email-valentin.longchamp@keymile.com> <1414537731.23458.120.camel@snotra.buserror.net> <5450AC85.40302@keymile.com> <20141113003418.GE2062@katana> <5465B285.7070005@keymile.com> <20141114082832.GA2180@katana> <1416274083.15957.96.camel@freescale.com> <20141125181347.GC9716@katana> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141125181347.GC9716@katana> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: Valentin Longchamp , Linux PowerPC Kernel , Linux device trees , Linux I2C , "Brunck, Holger" , "Boschung, Rainer" List-Id: devicetree@vger.kernel.org On Tue, 2014-11-25 at 19:13 +0100, Wolfram Sang wrote: > On Mon, Nov 17, 2014 at 07:28:03PM -0600, Scott Wood wrote: > > On Fri, 2014-11-14 at 09:28 +0100, Wolfram Sang wrote: > > > > > > > > > > If we're going to change the device tree I'd rather just add a property > > > > > to say what the prescaler is. > > > > > > > > We would however, leave the boards' device trees that use things like > > > > "fsl,mpc8543-i2c" as is and introduce the prescaler for the others requiring it. > > > > > > > > > > > > Now the drawback is that the driver would require a change, to parse this > > > > prescaler new prescaler property. Would this be OK from your point of view > > > > Wolfram ? If yes, I will send the patches for it. > > > > > > I don't think it is OK. > > > > Why? > > Because I thought it could be deduced. Then, a seperate property would > not be OK. > > > > I'd think it can be deduced from the compatible property. > > > > For almost all existing device trees it cannot be. > > Pity :( If we do introduce a new property, it should probably be > "clock-div". Grepping through binding documentation, that seems > accepted. We should ask DT maintainers, too, to be safe. > > > If you want something that will work without changing device trees, > > you'll need to use SVR to identify the SoC. > > The driver is doing that already, see mpc_i2c_get_sec_cfg_8xxx(). Dunno > if it makes sense to add to it for consistency reasons? That's not SVR, but sure. Better to avoid messing with existing device trees. -Scott -- 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