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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65EAAC432C3 for ; Mon, 2 Dec 2019 15:06:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40A952084F for ; Mon, 2 Dec 2019 15:06:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727417AbfLBPGI (ORCPT ); Mon, 2 Dec 2019 10:06:08 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:55771 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727413AbfLBPGH (ORCPT ); Mon, 2 Dec 2019 10:06:07 -0500 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1ibnH0-0003YA-EA; Mon, 02 Dec 2019 16:06:02 +0100 Received: from mfe by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1ibnGz-0005jR-Ng; Mon, 02 Dec 2019 16:06:01 +0100 Date: Mon, 2 Dec 2019 16:06:01 +0100 From: Marco Felsch To: Adam Thomson Cc: Guenter Roeck , "wim@linux-watchdog.org" , Support Opensource , "kernel@pengutronix.de" , "linux-watchdog@vger.kernel.org" Subject: Re: [PATCH] watchdog: da9062: add power management ops Message-ID: <20191202150601.r3qb3b3kaezlihee@pengutronix.de> References: <20191128171931.22563-1-m.felsch@pengutronix.de> <20191202105646.xzqzlu2jnel4qbuv@pengutronix.de> <20191202130314.dzne7eh2b5sb46c2@pengutronix.de> <1feb2b8e-af46-ffa9-873a-fd9b624294b9@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 15:54:37 up 17 days, 6:13, 29 users, load average: 0.13, 0.05, 0.01 User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: mfe@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-watchdog@vger.kernel.org Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org On 19-12-02 14:44, Adam Thomson wrote: > On 02 December 2019 13:38, Adam Thomson wrote: > > > On 12/2/19 5:27 AM, Adam Thomson wrote: > > > Hi Marco, > > > > > >>> Hmmm. Wouldn't that then be a board specific fix rather than this change? > > >>> Am concerned relying on software to reenable the watchdog on resume > > could > > >> allow > > >>> for a hang scenario potentially if that code never gets to execute. Other > > >>> systems shouldn't need this fix, assuming they don't have issues at the HW > > >>> level, so this this seems like it could be making those systems less robust. If > > >>> we are to do this at the driver level, maybe this should be an option through > > DT > > >>> to help faulty systems, but I'm thinking this shouldn't be default behaviour. > > >> > > >> I don't think that we should rely on the OTP values. Those values are > > >> set by Dialog, the SoM manufacturers or by the customer itself and the > > >> time shows that this is error prone too. At least if the customer or the > > >> SoM manufacturer don't ask the Dialog Support.. > > >> > > >> You're right with the (re-)enabling but there are other drivers using > > >> such an approach.. IMHO it is safer to go this way rather than trust > > >> the OTP and the PCB layout. I would rather add a dt-compatible to tell > > >> the driver to do nothing during suspend/resume e.g.: > > >> > > >> - dlg,use-hw-pm > > >> > > >> or something. Because the user needs to validate the PCB and the OTP > > >> values. > > > > > > The thing is the DT FW is supposed to be fairly static so I would rather not > > > enforce this change on users if they adopt a kernel version with this update in. > > > I also still think it's safer if the HW does this for us. I would have hoped for > > > most designs this would be caught in early bring up where it can be rectified > > > with minimal impact, although I'm guessing that's not the case in your scenario. > > > > > > > dla,use-sw-pm ? > > dla,hw-pm-broken ? > > Yes, I'd probably opt for 'dlg,use-sw-pm' or maybe 'dlg,manual-pm' to cover it. Okay, so we are all agree with the dlg,use-sw-pm? Regards, Marco > > > > > Guenter -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |