From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from am1outboundpool.messaging.microsoft.com (am1ehsobe004.messaging.microsoft.com [213.199.154.207]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "Microsoft Secure Server Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 1952D2C0093 for ; Tue, 17 Jul 2012 00:43:43 +1000 (EST) Message-ID: <50042891.20406@freescale.com> Date: Mon, 16 Jul 2012 09:43:29 -0500 From: Scott Wood MIME-Version: 1.0 To: Subject: Re: [PATCH] ppc44x/watchdog: Select WATCHDOG_NOWAYOUT option References: <1342147473-20231-1-git-send-email-lu.jiang@windriver.com> <50037762.4000800@windriver.com> In-Reply-To: <50037762.4000800@windriver.com> Content-Type: text/plain; charset="UTF-8" Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 07/15/2012 09:07 PM, Lu.Jiang wrote: > =E4=BA=8E 2012=E5=B9=B407=E6=9C=8813=E6=97=A5 19:50, Kumar Gala =E5=86=99= =E9=81=93: >> On Jul 12, 2012, at 9:44 PM, Jiang Lu wrote: >> >>> On PPC44x core, the WRC(Watchdog-timer Reset Control) field of TCR >>> of timer can not reset by software after set to a non-zero value. >>> Which means software can not reset the timeout behaviour of watchdog >>> timer. >>> >>> This patch selects WATCHDOG_NOWAYOUT option for 44x platforms to >>> indicate the watchdog timer can not be disabled once fired. >>> >>> Signed-off-by: Jiang Lu >>> --- >>> drivers/watchdog/Kconfig | 1 + >>> 1 files changed, 1 insertions(+), 0 deletions(-) >> I believe this is not 44x specific, but how Book-E watchdog is >> architected. >> >>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig >>> index 3709624..41f3dff 100644 >>> --- a/drivers/watchdog/Kconfig >>> +++ b/drivers/watchdog/Kconfig >>> @@ -1084,6 +1084,7 @@ config PIKA_WDT >>> config BOOKE_WDT >>> tristate "PowerPC Book-E Watchdog Timer" >>> depends on BOOKE || 4xx >>> + select WATCHDOG_NOWAYOUT if 44x >> This should probably be 'select WATCHDOG_NOWAYOUT if BOOKE' >=20 > On ppc44x's processor, if we disabled 'WATCHDOG_NOWAYOUT ' option. The > driver's release routine will try to disable the watchdog , by clearing > the WIE & WTDP field in TCR. > Since the ppc44x's watch dog can not reset by software, such operation > only set the timeout value(WDTP) to minimum, and cause the system reboo= t > immediately. >=20 > I checked ppc 476, 405 & 450's manual, these document said the > WRC(Watchdog-timer Reset Control) field of TCR of timer > can not reset by software after set to a non-zero value. I think all > ppc44x core should got same limitation. This is (supposed to be) true on FSL e500 as well. > While on FSL's platform, we did not met such issue. You tested this and were able to clear WRC on an e500-based chip? Which one? -Scott