From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mitch Bradley Subject: Re: [RFC 2/2] ARM:Tegra: Device Tree Support: Initialize audio card gpio's from the device tree. Date: Sun, 29 May 2011 20:18:09 -1000 Message-ID: <4DE336A1.5040509@firmworks.com> References: <20110527205444.21000.90209.stgit@riker> <20110527205721.21000.78599.stgit@riker> <20110528012427.GB5971@opensource.wolfsonmicro.com> <20110530033826.GE4130@opensource.wolfsonmicro.com> <20110530061155.GC23517@ponder.secretlab.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110530061155.GC23517-e0URQFbLeQY2iJbIjFUEsiwD8/FfD2ys@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: Grant Likely Cc: "glikely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , Mark Brown , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Olof Johansson , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 5/29/2011 8:11 PM, Grant Likely wrote: > On Mon, May 30, 2011 at 11:38:27AM +0800, Mark Brown wrote: >> On Sun, May 29, 2011 at 08:11:34PM -0700, Olof Johansson wrote: >>> On Fri, May 27, 2011 at 6:24 PM, Mark Brown >> >>>> This is a step back from the usability of the existing platform data - >>>> the platform data uses a series of individually named GPIOs while this >>>> uses an array of GPIO numbers with magic indexes. The fact that you >>>> need comments explaining what the functions of the array elements are >>>> is a bit of a red flag here. >> >>> Agreed, I had similar concerns with the sdhci bindings where it used a >>> 3-element array of gpios instead of the previous named ones. I was >>> told it's common practice to do it that way though? Seems like a step >>> backwards to me. :( >> >> Interesting... what was the reasoning behind this? It's a definite >> step backwards but it does explain my major concern with the new batch >> of device tree patches. > > The binding for gpios was defined a few years ago and it is in fairly > wide use within the powerpc sphere. The design followed the pattern > established for specifying irqs, and in that regard satisfied the > principle of least surprise. > > That said, it isn't a very large leap to go from a single 'gpios' > property to allowing multiple named gpios properties with meaningful > names, particularly if they are fully specified by the device > binding, and they follow exactly the same binding semantics as the > existing 'gpios' proprety (phandle + gpio specifier). > > Personally, I'm /cautious/ about saying okay to extending the binding, > simply because once the extension is in use it is really hard to go > back on it, but I cannot think of any reason why this particular case > wouldn't be a good idea. Anyone have thoughts on this? Ben? Mitch? I'm currently dealing with an SoC that has over a hundred GPIOs. Whatever we choose, I think it should be able to handle an insane number of GPIOs without getting any more cumbersome that is necessary. > > g. >