From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [PATCH 08/17] watchdog: qcom: configure BARK time in addition to BITE time Date: Thu, 24 Mar 2016 09:17:54 -0700 Message-ID: <20160324161754.GA6515@roeck-us.net> References: <1458770712-10880-1-git-send-email-mmcclint@codeaurora.org> <1458770712-10880-9-git-send-email-mmcclint@codeaurora.org> <20160323224226.GD18567@codeaurora.org> <19DAEEE1-1019-49FB-A921-4311F592A7EC@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from bh-25.webhostbox.net ([208.91.199.152]:35850 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751303AbcCXQR5 (ORCPT ); Thu, 24 Mar 2016 12:17:57 -0400 Content-Disposition: inline In-Reply-To: <19DAEEE1-1019-49FB-A921-4311F592A7EC@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Matthew McClintock Cc: Stephen Boyd , andy.gross@linaro.org, linux-arm-msm@vger.kernel.org, qca-upstream.external@qca.qualcomm.com, Wim Van Sebroeck , "open list:WATCHDOG DEVICE DRIVERS" , open list On Thu, Mar 24, 2016 at 10:46:42AM -0500, Matthew McClintock wrote: > On Mar 23, 2016, at 5:42 PM, Stephen Boyd wrot= e: > >=20 > > On 03/23, Matthew McClintock wrote: > >> For certain parts and some versions of TZ, TZ will reset the chip > >> when a BARK is triggered even though it was not configured here. S= o > >> by default let's configure this BARK time as well. > >>=20 > >=20 > > Why isn't TZ configuring the bark time to what it wants? I'm lost > > why we have to do this for them. >=20 > So it was done like this to ensure we had a valid upgrade. The bootlo= ader is using the watchdog to ensure the system is bootable and if not = it will revert back to the working images. >=20 > Bottom line is, for some versions of TZ out there, if we enable watch= dog coming out of boot the bark time is already configured by the boot = loader and TZ is configured to intercept this interrupt and do some reg= ister saving (for crashdump) and we end up getting a watchdog reset dur= ing boot. >=20 > It=E2=80=99s even a little more complex, because in order for the TZ = to save the registers you need to pad the BITE time a bit higher than t= he BARK time, but I was leaving that for another day. >=20 Sounds like an op[timal target for using pretimeout ? Guenter