From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5C59C433FE for ; Thu, 20 Oct 2022 13:08:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=RZrG0nV0pO9v4/XrBOOt24zvNMFP7nP+15XkhiPuzsE=; b=agwp9DDZpc+f5a N0DpC2nN7cl9PUxGjgKL+kJHc3T+6yLC0mmFlBJ2UhBRK8QshI8YKB93qXKwIaWy9NI3tZhgDuDBE DkVtjbWUmVBoltrmwB2VtH6MbQ8A514cGdXknoRcGP4c0o5e+0v97LHyumgCQDViseAmxMxEjtrYS q/3GhzTHmfWY7i4f7GQlpVzjxy0b3DqriK2n2C4KfCsUy17bYjNFVYYdzoJO8SpVbmNAHRDXlUXJK KeJn/VfRAxblvOzm3MECJzQaMuni3gOTg27i8RDt5aVd+QpcyxH9+kAxEEWdPqdYoQmeclLvzuPXc ZfOBUz/7MTrk3XRDbqrA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1olVGW-00FGEy-9W; Thu, 20 Oct 2022 13:07:16 +0000 Received: from cpanel.siel.si ([46.19.9.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1olVEi-00FEts-LY for linux-arm-kernel@lists.infradead.org; Thu, 20 Oct 2022 13:05:27 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=norik.com; s=default; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=zBfRLPHN7pD803Ec207ScFoVXllUCYrqmPtJ5RGSCFA=; b=QsSl+Ef1C+rut7w+c7b0dct0SD atVHCLVro1DJl6G9te22fJy+DzsDP+Xfe23qfrrOixaPRk/rH+I8KZVtbpLzag7pQJYiMaFUuf+sg +MVFx/Nd98mBVzOVJhXvDhSqeRlSbi0LaSTtaKIv+ARSw2JfbSmZXDPgouiu2hpk1GoWx5pxMy4se qgmR9wvExF51hUCFZIkOc0x5+Nle803rE+FaBcUzNbf9jpHdoL1p1sv6/wSWiqQWx+09avawGTlXW QJpxZI37YeN/LcXwSwsCscGuC07wOfdfYN/jCT1utdxXzF00mMX2ZZHu0w5GSp42AWmcic4T98FNv 2nBR5lUQ==; Received: from [89.212.21.243] (port=52854 helo=[192.168.69.85]) by cpanel.siel.si with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.95) (envelope-from ) id 1olVEb-00DwvZ-3d; Thu, 20 Oct 2022 15:05:17 +0200 Message-ID: <1a3a1c8c-8baf-ef70-9e5b-e817bb14cfad@norik.com> Date: Thu, 20 Oct 2022 15:05:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH 2/3] dt-bindings: watchdog: fsl-imx: document suspend in wait mode Content-Language: en-GB To: Alexander Stein , Krzysztof Kozlowski Cc: linux-watchdog@vger.kernel.org, linux-arm-kernel@lists.infradead.org, shawnguo@kernel.org, linux@roeck-us.net, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-imx@nxp.com, festevam@gmail.com, kernel@pengutronix.de, s.hauer@pengutronix.de, wim@linux-watchdog.org, robh+dt@kernel.org References: <20221019111714.1953262-1-andrej.picej@norik.com> <143f1466-e34a-254d-4e6e-fefa17ad1390@norik.com> <24401572.EfDdHjke4D@steina-w> From: Andrej Picej In-Reply-To: <24401572.EfDdHjke4D@steina-w> X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - cpanel.siel.si X-AntiAbuse: Original Domain - lists.infradead.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - norik.com X-Get-Message-Sender-Via: cpanel.siel.si: authenticated_id: andrej.picej@norik.com X-Authenticated-Sender: cpanel.siel.si: andrej.picej@norik.com X-Source: X-Source-Args: X-Source-Dir: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221020_060525_224386_DF02C5AB X-CRM114-Status: GOOD ( 27.58 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 20. 10. 22 14:41, Alexander Stein wrote: > Am Donnerstag, 20. Oktober 2022, 14:36:10 CEST schrieb Andrej Picej: >> On 20. 10. 22 14:18, Krzysztof Kozlowski wrote: >>> On 20/10/2022 02:23, Andrej Picej wrote: >>>> Hi Alexander and Krzysztof, >>>> >>>> hope I can reply to both questions here. >>>> >>>> On 19. 10. 22 17:51, Krzysztof Kozlowski wrote: >>>>> On 19/10/2022 09:00, Alexander Stein wrote: >>>>>> Hello Andrej, >>>>> >>>>>> Am Mittwoch, 19. Oktober 2022, 13:17:13 CEST schrieb Andrej Picej: >>>>> Missing commit msg. >>>>> >>>>>>> Signed-off-by: Andrej Picej >>>>>>> --- >>>>>>> >>>>>>> Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml | 5 >>>>>>> +++++ >>>>>>> 1 file changed, 5 insertions(+) >>>>>>> >>>>>>> diff --git >>>>>>> a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml >>>>>>> b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml index >>>>>>> fb7695515be1..01b3e04e7e65 100644 >>>>>>> --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml >>>>>>> +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml >>>>>>> >>>>>>> @@ -55,6 +55,11 @@ properties: >>>>>>> If present, the watchdog device is configured to assert its >>>>>>> external reset (WDOG_B) instead of issuing a software reset. >>>>>>> >>>>>>> + fsl,suspend-in-wait: >>>>>>> + $ref: /schemas/types.yaml#/definitions/flag >>>>>>> + description: | >>>>>>> + If present, the watchdog device is suspended in WAIT mode. >>>>>>> + >>>>>>> >>>>>>> required: >>>>>>> - compatible >>>>>>> - interrupts >>>>>> >>>>>> What is the condition the watchdog is suspended in WAIT mode? Is this >>>>>> specific to SoC or platform or something else? >>>> >>>> Sorry, what exactly do you mean by condition? >>> >>> Ugh, I also cannot parse it now... > > Sorry, Krzysztof already asked the right question: When does one want to > enable/disable this feature? > >>>> When the property >>>> "fsl,suspend-in-wait" is set the watchdog is suspended in WAIT mode, so >>>> this is defined by the user. Didn't want to apply it for all the >>>> supported machines since there could be devices which depend on watchdog >>>> triggering in WAIT mode. We stumbled on this problem on imx6 devices, >>>> but the same bit (with the same description) is found on imx25, imx35, >>>> imx50/51/53, imx7 and imx8. >>> >>> I meant, what is expected to happen if you do not enable this bit and >>> watchdog triggers in WAIT mode? IOW, why someone might want to enable or >>> disable this property? >> >> If this is not enabled and you put the device into the Suspend-to-idle >> mode the device resets after 128 seconds. If not, the device can be left >> in that state for infinite time. I'm guessing you want me to better >> explain the property in device tree docs right? >> I can do that in v2. >> >>>>> And what happens else? When it is not suspended in WAIT mode? >>>> >>>> When you put the device in "freeze"/"Suspend-To-Idle" low-power mode the >>>> watchdog keeps running and triggers a reset after 128 seconds. So the >>>> maximum length the device can stay in this mode is limited to 128 >>>> seconds. >>> >>> And who wakes up the system before 128 seconds? IOW is there a use case >>> of not enabling this property? >> >> Well I can think of one, system can be woken up by some other interrupt. >> Like RTC which triggers interrupt (for example every 10s). So if this >> property is left disabled the watchdog can handle errors where other >> wakeup sources don't trigger interrupt or if the system is unable to >> wake from low-power state. In that case the watchdog will do a hard >> reset of the device. >> >> But I'm not really sure if anybody uses this, just wanted to make sure >> that we keep the default behaviour as it is, since this driver is used >> by many devices and for quite some time. > > This sounds more like (application) configuration. If so this should not be > configured in device tree, IMHO. > Do you have an idea where should it be configured? Just keep in mind that this can not be configured at runtime, since this is write-once bit so any configuration changes regarding this functionality can not be done. Basically if I can sum up the problem: Without this property enabled, the WDW bit is left unset: $ echo freeze > /sys/power/state #device enters Suspend-to-idle, watchdog is left running and the device resets after 128 seconds in this state With this property set, the WDW bit is set at watchdog initialization: $ echo freeze > /sys/power/state #device enters Suspend-to-idle, watchdog is suspended and the device can be left in this state until some other wakeup source triggers interrupt. Thanks, Andrej _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel