Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757239Ab3FSSPT (ORCPT ); Wed, 19 Jun 2013 14:15:19 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:40880 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756741Ab3FSSPR (ORCPT ); Wed, 19 Jun 2013 14:15:17 -0400 Message-ID: <51C1F531.3050205@wwwdotorg.org> Date: Wed, 19 Jun 2013 12:15:13 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Linus Walleij CC: Christian Ruppert , Patrice CHOTARD , "linux-kernel@vger.kernel.org" , Grant Likely , Rob Herring , Rob Landley , Sascha Leuenberger , Pierrick Hascoet , "devicetree-discuss@lists.ozlabs.org" , "linux-doc@vger.kernel.org" , Alexandre Courbot Subject: Re: [PATCH 1/4] Make non-linear GPIO ranges accesible from gpiolib References: <20130618092516.GC18663@ab42.lan> <1371547751-13873-1-git-send-email-christian.ruppert@abilis.com> In-Reply-To: X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2838 Lines: 61 On 06/19/2013 06:03 AM, Linus Walleij wrote: > On Tue, Jun 18, 2013 at 11:29 AM, Christian Ruppert > wrote: > >> This patch adds the infrastructure required to register non-linear gpio >> ranges through gpiolib and the standard GPIO device tree bindings. >> >> Signed-off-by: Christian Ruppert > > I'm basically fine with this, but would like Stephen's ACK if possible. > >> +In addition, named groups of pins can be mapped to pin groups of a given >> +pin controller: >> + >> + gpio_pio_g: gpio-controller@1480 { >> + #gpio-cells = <2>; >> + compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank"; >> + reg = <0x1480 0x18>; >> + gpio-controller; >> + gpio-ranges = <&pinctrl1 0 0 0>, <&pinctrl2 3 0 0>; >> + gpio-ranges-group-names = "foo", "bar"; >> + }; >> + >> +where, >> + &pinctrl1 and &pinctrl2 is the phandle to the pinctrl DT node. >> + >> + The following value specifies the base GPIO offset of the pin range with >> + respect to the GPIO controller's base. The remaining two values must be >> + 0 to indicate that a named pin group should be used for the respective >> + range. The number of pins in the range is the number of pins in the pin >> + group. > > So while this works, these zeroes seem a bit awkward, but maybe > it's the only way? > > I'm not good enough on device tree conventions, but isn't this possible: > > gpio-ranges = <&pinctrl1 0>, <&pinctrl2 3>; > gpio-ranges-group-names = "foo", "bar"; > > Since we don't have any #gpio-ranges-cells or anything like that I > guess we can define this to have a flexible number of cells > depending on use case? If we're willing to have gpio-ranges be either *all* group names, or *all* IDs, we can define the format of gpio-ranges to have two cells (phandle and GPIO number) if the property gpio-ranges-group-names exists, but four cells (phandle, GPIO number, pin number, count) otherwise. However, that's a little restrictive, since then what if one GPIO controller is hooked to two different pinmux controllers, and you want to use different formats for the references to each. A #gpio-ranges-cells in the target of the phandle would allow this, but I don't think this is something the pinctrl node should dictate to those who reference it; it's quite legitimate for a GPIO node to use the pure numeric mapping even if the pin controller happens to expose some pin groups that allow you to do the mapping by name. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/