From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752824AbbJWQI2 (ORCPT ); Fri, 23 Oct 2015 12:08:28 -0400 Received: from mail-gw1-out.broadcom.com ([216.31.210.62]:61121 "EHLO mail-gw1-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750904AbbJWQI0 (ORCPT ); Fri, 23 Oct 2015 12:08:26 -0400 X-IronPort-AV: E=Sophos;i="5.20,187,1444719600"; d="scan'208";a="78623775" Subject: Re: [PATCH 05/11] dt-binding: Add ngpios property to GPIO controller node To: Laurent Pinchart , Rob Herring References: <1445233398-27129-1-git-send-email-pramodku@broadcom.com> <3735458.2h6HCQhAOs@avalon> <2123166.E4KEJx3AQ2@avalon> CC: Pramod Kumar , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , "Scott Branden" , Russell King , Linus Walleij , "linux-gpio@vger.kernel.org" , BCM Kernel Feedback , Jason Uy , Masahiro Yamada , Thomas Gleixner , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Jonas Gorski From: Ray Jui Message-ID: <562A5B75.7010804@broadcom.com> Date: Fri, 23 Oct 2015 09:08:21 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <2123166.E4KEJx3AQ2@avalon> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/23/2015 6:02 AM, Laurent Pinchart wrote: > Hi Rob, > > On Friday 23 October 2015 06:51:28 Rob Herring wrote: >> On Fri, Oct 23, 2015 at 4:08 AM, Laurent Pinchart wrote: >>> On Thursday 22 October 2015 18:41:05 Rob Herring wrote: >>>> On Thu, Oct 22, 2015 at 1:52 PM, Ray Jui wrote: >>>>> On 10/22/2015 11:43 AM, Rob Herring wrote: >>>>>> On Mon, Oct 19, 2015 at 12:43 AM, Pramod Kumar wrote: >>>>>>> Add ngpios property to the gpio controller's DT node so that >>>>>>> controller driver extracts total number of gpio lines present in >>>>>>> controller from DT and removes dependency on driver. >>>>>>> >>>>>>> Signed-off-by: Pramod Kumar >>>>>>> Reviewed-by: Ray Jui >>>>>>> Reviewed-by: Scott Branden >>>>>>> --- >>>>>>> >>>>>>> Documentation/devicetree/bindings/pinctrl/brcm,cygnus-gpio.txt | 5 >>>>>>> +++ >>>>>>> 1 file changed, 5 insertions(+) >>>>>>> >>>>>>> diff --git >>>>>>> a/Documentation/devicetree/bindings/pinctrl/brcm,cygnus-gpio.txt >>>>>>> b/Documentation/devicetree/bindings/pinctrl/brcm,cygnus-gpio.txt >>>>>>> index f92b833..655a8d7 100644 >>>>>>> --- a/Documentation/devicetree/bindings/pinctrl/brcm,cygnus-gpio.txt >>>>>>> +++ b/Documentation/devicetree/bindings/pinctrl/brcm,cygnus-gpio.txt >>>>>>> >>>>>>> @@ -10,6 +10,9 @@ Required properties: >>>>>>> Define the base and range of the I/O address space that >>>>>>> contains >>>>>>> >>>>>>> the Cygnus >>>>>>> >>>>>>> GPIO/PINCONF controller registers >>>>>>> >>>>>>> +- ngpios: >>>>>> + Total number of GPIOs the controller provides >>>>>> >>>>>> This must be optional for compatibility and the driver needs to handle >>>>>> it not present. >>>>> >>>>> You meant to be compatible with existing Cygnus devices, correct? >>>>> >>>>> Just to clarify, here you suggest we still leave the existing hard >>>>> coded ngpios in the driver, in order to be compatible with all existing >>>>> Cygnus devices (while the Cygnus device tree changes to use ngpio is >>>>> still being merged and through different maintainer), and have all new >>>>> iProc SoCs switch to use ngpios from device tree, right? >>>> >>>> Yes, an existing dtb should continue to work with a new kernel. You >>>> can add the DT property to the older devices too and then eventually >>>> remove the hard coded values some time in the future. That could be >>>> immediately (don't care about compatibility at all), a couple of >>>> kernel cycles, never... It all depends on users of the impacted >>>> platforms. >>> >>> But shouldn't the property still be documented as required to ensure that >>> new DTs always include it ? >> >> Good point. If the intent is to eventually remove it from the driver, >> then yes. We probably need "required for new designs" as a category or >> maybe "recommended"? The wording is not so important here, but I'm >> thinking about as we try to standardize the naming. > > Required for new designs sounds better than recommended. Or maybe something > like "Required (optional for backward compatibility)". > Yes, it should be phrased as "required for new designs" because all new iProc SoCs using this GPIO driver need to have this in DT. Thanks, Ray