Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967093AbbLQPcO (ORCPT ); Thu, 17 Dec 2015 10:32:14 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:40231 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751151AbbLQPcM (ORCPT ); Thu, 17 Dec 2015 10:32:12 -0500 Subject: Re: [PATCH v4 1/2] watchdog: imx2_wdt: add external reset support via 'ext-reset-output' dt prop To: Tim Harvey , Wim Van Sebroeck References: <1446758362-11702-1-git-send-email-akshay.bhat@timesys.com> <1446758362-11702-2-git-send-email-akshay.bhat@timesys.com> <20151105222325.GA26159@roeck-us.net> <20151106220249.GA19791@roeck-us.net> <565F4244.7090502@timesys.com> Cc: linux-watchdog@vger.kernel.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Shawn Guo , Sascha Hauer , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" , justin.waters@timesys.com, Lucas Stach , Fabio Estevam , Stefan Roese , Akshay Bhat From: Guenter Roeck Message-ID: <5672D572.9080104@roeck-us.net> Date: Thu, 17 Dec 2015 07:32:02 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4684 Lines: 125 On 12/17/2015 07:02 AM, Tim Harvey wrote: > On Wed, Dec 2, 2015 at 12:54 PM, Tim Harvey wrote: >> >> On Wed, Dec 2, 2015 at 11:11 AM, Akshay Bhat wrote: >>> >>> >>> On 11/06/2015 05:02 PM, Guenter Roeck wrote: >>>> >>>> On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote: >>>>> >>>>> On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck wrote: >>>>>> >>>>>> On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: >>>>>>> >>>>>>> From: Tim Harvey >>>>>>> >>>>>>> The IMX6 watchdog supports assertion of a signal (WDOG_B) which >>>>>>> can be pinmux'd to an external pin. This is typically used for boards >>>>>>> that >>>>>>> have PMIC's in control of the IMX6 power rails. In fact, failure to use >>>>>>> such an external reset on boards with external PMIC's can result in >>>>>>> various >>>>>>> hangs due to the IMX6 not being fully reset [1] as well as the board >>>>>>> failing >>>>>>> to reset because its PMIC has not been reset to provide adequate >>>>>>> voltage for >>>>>>> the CPU when coming out of reset at 800Mhz. >>>>>>> >>>>>>> This uses a new device-tree property 'ext-reset-output' to indicate the >>>>>>> board has such a reset and to cause the watchdog to be configured to >>>>>>> assert >>>>>>> WDOG_B instead of an internal reset both on a watchdog timeout and in >>>>>>> system_restart. >>>>>>> >>>>>>> [1] >>>>>>> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/333689.html >>>>>>> >>>>>>> Cc: Lucas Stach >>>>>>> Signed-off-by: Tim Harvey >>>>>>> --- >>>>>>> .../devicetree/bindings/watchdog/fsl-imx-wdt.txt | 2 ++ >>>>>>> drivers/watchdog/imx2_wdt.c | 20 >>>>>>> ++++++++++++++++++-- >>>>>>> 2 files changed, 20 insertions(+), 2 deletions(-) >>>>>>> >>>>>>> diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt >>>>>>> b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt >>>>>>> index 8dab6fd..9b89b3a 100644 >>>>>>> --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt >>>>>>> +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt >>>>>>> @@ -9,6 +9,8 @@ Optional property: >>>>>> >>>>>> >>>>>> properties ? >>>>>> >>>>>>> - big-endian: If present the watchdog device's registers are >>>>>>> implemented >>>>>>> in big endian mode, otherwise in native mode(same with CPU), for >>>>>>> more >>>>>>> detail please see: >>>>>>> Documentation/devicetree/bindings/regmap/regmap.txt. >>>>>>> +- ext-reset-output: If present the watchdog device is configured to >>>>>>> assert its >>>>>> >>>>>> >>>>>> Should that have a vendor prefix ? Also, not sure if "-output" >>>>>> has any real value in the property name. "fsl,external-reset", maybe ? >>>>> >>>>> >>>>> Hi Guenter, >>>>> >>>>> I don't see why a vendor prefix is necessary - its a feature of the >>>>> IMX6 watchdog supported by this driver to be able to trigger an >>>>> internal chip-level reset and/or an external signal that can be hooked >>>>> to additional hardware. >>>>> >>>> Sounded like vendor specific to me, but then I am not a devicetree >>>> maintainer, >>>> so I am not an authority on the subject. >>> >>> >>> Devicetree maintainers, >>> >>> Any thoughts? >>> >>> Tim, >>> >>> After looking at all the other watchdog drivers, it does not appear that >>> there is any other processor which uses a similar feature. Since imx is the >>> only processor that appears to support this feature, it might make sense in >>> making this vendor specific. If in the future it is found more processors >>> support a similar functionality, it can be revisited and moved out from >>> being vendor specific? >>> >> >> I'm certainly no expert on device-tree policy. I understand your >> point, but realize that the driver in question is imx2_wdt.c >> (compatible = "fsl,imx21-wdt"). This is an IP block inside the silicon >> of only Freescale chips, so its not like a future omap chip would be >> using this driver - only fsl devices. So why would it need a 'vendor' >> property any more than its other properties? >> >> Regards, >> >> Tim > > Wim, > > Does the lack of response mean overwhelming approval? > > I haven't heard any valid complaints - what does it take to get this approved? > Tim, Do you have an Ack from a devicetree maintainer ? I don't recall seeing one. Thanks, Guenter -- 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/