From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH v3 4/4] mmc: sdhci-esdhc-imx: add device tree probe support Date: Wed, 13 Jul 2011 11:09:40 -0500 Message-ID: <20110713110940.460a7966@schlenkerla.am.freescale.net> References: <1309970870-13336-1-git-send-email-shawn.guo@linaro.org> <1309970870-13336-5-git-send-email-shawn.guo@linaro.org> <20110706210518.GD5371@ponder.secretlab.ca> <20110713155212.GB7875@oksana.dev.rtsoft.ru> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110713155212.GB7875@oksana.dev.rtsoft.ru> Sender: linux-mmc-owner@vger.kernel.org To: Anton Vorontsov Cc: Grant Likely , patches@linaro.org, devicetree-discuss@lists.ozlabs.org, linux-mmc@vger.kernel.org, Chris Ball , linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org On Wed, 13 Jul 2011 19:52:12 +0400 Anton Vorontsov wrote: > On Wed, Jul 06, 2011 at 03:05:18PM -0600, Grant Likely wrote: > > On Thu, Jul 07, 2011 at 12:47:50AM +0800, Shawn Guo wrote: > > > +- cd-gpios : Specify GPIOs for card detection > > > +- wp-gpios : Specify GPIOs for write protection > [...] > > > + cd-gpios = <&gpio0 6 0>; /* GPIO1_6 */ > > > + wp-gpios = <&gpio0 5 0>; /* GPIO1_5 */ > > Is there any particular reason why we started using named GPIOs > in the device tree? To me, that's quite drastic change... should > we start using named regs and interrupts as well? Personally, I > don't think that the idea is great, as now you don't know where > to expect memory resources, interrupt resources and, eventually > GPIO resources. Just check the binding, and you'll know. :-) It makes it easier to deal with cases where some resources are optional, especially when dealing with a binding for a family of devices that grows over time, and helps avoid resources being mismatched since order no longer matters. > Just a few disadvantages off the top of my head: > > - You can't statically validate your device tree for correctness. > Today dtc checks #{address,size}-cells sanity for 'regs' and > 'ranges'; The vast majority of stuff in the device tree already cannot be checked in this manner, without adding binding knowledge to dtc. Perhaps it could check things that end in "-gpios", "-regs", etc., if we avoid adding new properties that match those patterns that aren't what they appear to be, and let dtc know about any existing cases. > - You can't automatically convert named resources into 'struct > resource *', as we do for platform devices now; So add named resource support to platform devices. :-) -Scott